TOSLINK: That one consumer fiber optic standard

I laughed out loud at gold plated connectors on an optical cable. 🤣

There’s an advantage to using fibre optic that went unsung here; the ability to entirely sidestep ground loop problems regardless of where things are plugged! This saved me a great deal of headaches when it was possible

Yep, amazing that TOSLINK and S/PDIF are still being used. Even more amazing is that the original MIDI standard from 1982 is still actively used on new musical devices. RCA connectors are still used after being invented around 1937 to connect phonographs to RCA radios. But to me the grand champion longest-running interface is the phone plug (or jack), still used on electric instruments, headphones, mixing consoles, etc., which descends from a telephone switchboard jack first used around 1877.

“Yelling at computers to turn the lights off...” you, sir, have been cracking me up more and more!

My ancient computer motherboard has quite a noticeable noise floor on the headphone out plugs. It also transmits noise over USB to cheap DAC/Amps I've used in the past. Sending TOSLINK to cheap DACs removed all noise floor. This was a useful fix that served me well for many years, and an example of using optical signal to electrically isolate components.
Another useful "feature" of using a motherboard digital audio out is that you can keep the outputs set as default without them being auto disabled (windows) or having to deal with changing output devices (alsa headaches...).

My old Sony 5.1 surround sound system (circa 2004) makes use of TOSLINK, and it connects to my Chinesium SMART TV (circa 2020) without any issues and provides excellent sound quality. This video did a perfect job of explaining what was going on behind the scenes, and it makes me happy that old standards like these are still applicable and seamlessly integrate with today's technology.

something something
ground loops
something
Fun fact! I ran across a forum thread where someone was having a ground loop issue with a coax S/PDIF connection, and when someone suggested they switch to an optical connection to avoid that, _another_ entirely helpful and not-at-all pretentious person went off about how terrible optical connections are because of bandwidth and clock jitter.
*_You simply can't win_*

I love your channel so much. Your personality is engaging and unique. Your brand of witty, dry humor and the deep knowledge of the subject matter is as good as any on the platform. I would bet that a persistent desire to satisfy your insatiable natural curiosity has endowed you with a wealth of knowledge. Your intelligent and thoughtful presentation is very much appreciated by many people, I'm sure!

It was great for Mini disc recording, since you got an automatic sync and autostart of the recording as soon as you pressed play on your cd-player (after toggling the rec switch on the Mini-disc-player, to ready the Mini-disc for the incoming digital signal). Also all the songs names and track number automatically got transferred as well! Really neat!

MIDI was invented in 1983 as well! A rare case of an entire industry deciding there needs to be a single standard, and then making a single standard and sticking to it.

I like how optical also has a role in AC/DC electronics by means of being optocouplers. Isolating two sides of an electronic circuit avoiding stuff like ground loops in things like regulated power supplies.

Apple adopted Toslink starting on on the PowerMac G5 in 2003, up through the Mac Pro, until 2012. Also mini-Toslink, on the PowerBook G4 in 2005, and it remained in the MacBook Pro line until mid 2015. As well as the original MacBook line from 2005 to 2010. At the time I thought for sure they were going to release an iPod with some kind of Toslink/optical audio based headphones (for just $199 lol).

Imagine if they'd somehow found an overcomplicated way to get the actual laser reflection off the CD directly into the toslink cable

I loved using the toslink on my ps2 and 3 since the other connector ports on my reciever i had at the time were full with other stuff. Great for good game audio.

Nearly three years later TC is still educating and entertaining me.

Sony's higher end CD Walkmans had the capability to read CD-text. Also they had optical outs via mini-TosLink. If you had a mid to high end MD Walkman (called portable MD Deck by Sony), you could copy the CD and the CD-Text via the Toslink cable with amazing sound and all the tags intact. It was amazing at that time. MD still sounds amazing when fed from a good audio source though.

Mini TOSLink is incredibly common. Even my $20 RCA in/out audio interfaces have optical outs in the 3.5mm jacks, as do 3/5 of my laptops. Every TOSlink cable I ever bought came with a little clear lightpipe adapter that fits on to make it a 3.5mm form factor.

Now that I think about it, many laptops and tv-s I've seen over the years had one jack that had light coming out of it and I always assumed it's there to help you find it in the dark and tell it apart as the main audio output.

As a low voltage system engineer I have to say this video is an absolute delight. The explanation of the transition from the pits in the CD all the way to the RCA line out was just so comprehensive. I'm saving This video to send to future trainees. Thank you for your knowledge.

That's interesting. For some reason I always thought these transmitted analogue fiberoptic signals. Even my modern X570 chipset PC Motherboard has a TOSLINK Optical S/PDIF port on the rear I/O panel. I know the connector has been around since I was a kid, but I thought there was just.. more to it.

TOSlink is still alive today (and probably will be for a long time) because it's used on professional audio equipment to transmit digital audio over adat lightpipe instead of spdif, midi and wordclock, often all from the same port. It's extremely useful.

I've seen quite a few of your videos, but this was certainly a highlight regarding entertainment!
"as dark as the future of windows phone" had me laugh out loud and your reaction to gold plated toslink connectors was priceless! 😂
(and of course I've learned a lot that I didn't know before)

Watched this video many times over the last few years. I just today noticed you calling HDMI as "Handy Dandy Movie Input". It tickled me so much that it compelled me to comment and therefore break my 15 year streak of following the Prime Directive on Clip-Share. Love this channel and your work.

Been using optical audio for 10 years. I like it despite the very tiny amount of delay that's sometimes noticeable but often times not.

Toslink is a godsend for connecting certain types of consumer audio equipment together to avoid ground loops.

As an enthusiastic Hi-Fi Nerd in the early 2000's I was already aware of Mini-Toslink thanks to the wonders of Minidisc, but many people I worked with in the audio-visual installation industry first became aware of it thanks to Foxtel, Australia's Murdoch-owned monopoly cable TV provider. That time period saw a big marketing push to increase subscriber numbers which roughly coincided with the introduction of a new low-profile cable box manufactured by Pace. The rear panel featured 2 x SCART sockets mounted side-by-side (an interesting model choice considering that SCART connections on consumer-grade equipment sold in Australia were/are exceedingly rare) along with a composite baseband RCA jack, a SPDIF RCA jack... and a mysterious 3.5mm hole between the SCART sockets which glowed with a red light.
The Foxtel contractor's SOP was to stick a SCART-to-composite adaptor in the "TV" output socket and hook it up to the TV or AV receiver with a bog-standard 3 x RCA lead, then get out of there as quickly as possible before the client started asking questions about picture/sound quality. Specialist installers like myself would swap this for a SCART-to-Component (Y-Pb-Pr) adaptor and a 75-ohm coax for the SPDIF connection... unless the receiver didn't have a spare digital coax socket available, in which case you'd have to go hunting through the van for that Mini-Toslink to Toslink cable that you know you've got in there somewhere, or else start reconfiguring the cabling/connections to free up a coax socket. The Mini-Toslink was often a huge timesaver!

You can get toslink multi-input selectors and they're 100% mechanical, you just rotate a dial that changes which hole the light goes through.

Love toslink. Still then only standard that lets me connect modern devices that you mentioned (TV, Streaming box, Consoles) to my old school stereo amps.

I've been a tech nerd for years and have never heard of mini-toslink!!!! I still use toslink on my home equipment today. I love it!

I recently came across non-toslink S/PIDF when I ran out of digital optical ins on my second-hand early 00s AVR, and realized there was this digital coaxial in that used a normal RCA cable. Needless to say, this video cleared things up greatly.

You are throwing some next-level shade here, Alec! Toshiba HD-DVD. Windows Phone.
- This stuff is my business but I always learn something from your videos.
- Your shirt.
- The mirrored screen flips.
You're killing me here. Thank you!

Coming from the networking world, that maximum cable length thing is super interesting. In networking, range is actually the main advantage of optics. No matter how good your quality control is, losses from resistance and inductance limit practical range to 50-100m (shorter at the higher bitrates), while fiber runs can achieve runs in the 1-10km range in the budget of a small retail chain or school district. (Also super high throughput for trunk connections, but those transceivers are more pricey.)

I've been using Toslink to connect my living room PC to my surround sound receiver for years. The advantage is that it is just one cable going to the receiver, which drives a bunch of speakers that I already have set up

I’ve vaguely noticed the optical port on some of my stuff and I always just assumed it was something to do with attenuation. But now that I’m actually thinking about it I can’t think of a practical scenario for that…

This is the best description of audio connections I have seen in a long time even learned a few new things - always a good day when you learn something new!

I can imagine a digital optical link could still be useful when connecting a whole bunch of audio equipment together without worrying about ground loops

11:17 - Another advantage of TOSlink is it eliminates ground-voltage interference. If you have two devices connected that have slightly different ground-voltages for some reason, that difference will bleed through a copper cable and potentially interfere with anything else connected to the same grounding circuits inside each device. That won't happen with TOSlink.

You can also buy un-keyed TOSLINK cables now that fit into standard jacks regardless of how they are rotated. They are a lot easier to use on equipment you need to reach behind to make connections.

I wonder if putting monochromatic RGB LEDs and three filtered light sensors could work as a successor to toslink without replacing the cable
EDIT: oh wait the different colors probably have different dispersions and would be noticeably different under different lengths of cable

The only advantage I can think of for optical vs wired digital cables is that the bandwidth of standard RCA cables did not handle the multiple channel multiplexed optical signals and it would be tempting to use an audio RCA cable in a SPDIF port. Maybe the plan was to have multiple high frequency channels on optical toslink. I am sure that the optical cable was a marketing ploy much like the "gold plated" optical connectors though. I once saw a power strip in Fry's Electronics that said it was "Windows 95 Certified" on the box, obviously at a higher price.. People with more money than brains will buy the most expensive product they can find thinking it must be better. "Monster" cables were just such a marketing ploy.
EDIT: Another poster mentioned "No Ground Loops" as an advantage to optical cables which is certainly a huge advantage in an entertainment system containing a dozen or more electric components.

As a MD user in early 2000 and to this day in local community radio i can say the best feature i found with TOSlink is the ability for MD to change track automatic from source input while doing recordings. That i havent seen RCA line be able to do. But this only comes handy for very specific use-cases.

I’ve used pro audio equipment including high end AD/DA converters and had no idea optical sent the same signal as SPDIF. Optical sends multi channel audio which is nice but that’s a fun nugget.

the fact that there are TOSLINK cables with gold plated connectors just makes me want to die

I remember thinking the Mini Toslink was one of the coolest “features” of my first MacBook Pro back in 2007. I was wowed one “headphone” connector could also do optical!

The most important thing about light pipe audio is IMO that it can transmit multiple channels in one cable (when using ADAT / sample multiplexing [S-MUX]).

Yup I'm using toslink for my 2 PCs in spite that they both support HDMIs. It's mainly to isolate them electrically. You got the point that they share electrical sources anyway but it's more complicated than that... Just so people know, electrical leaks are quite common in old machines and they can damage sensitive amps (or so I think) or vice versa. I thought about this after getting multiple electrical shock from a cheap old PC I bought (the cause of which I'm too lazy to figure out just yet) Let me know if what I think is wrong...

I've had various sound cards in older PCs that had mini S/PDIF ports. I'd say it was common but not widely known.

Heh, i bought the very same Amazon basics cable used for this video just last week to run from my computer to my surround speakers. My reasoning for it though is I've apparently lost 2 of my 3 wired jacks on my mother board (Honestly think it's software but I couldn't sort it out). It's very annoying when you lose your center, sub, and rear speakers. The optical cable makes it all good though.

TOSLINK is the ultimate ground loop killer.
While SPDIF signal itself is not affected by interference and current loops, the act alone of connecting two devices via an SPDIF or any other cable that happens to connect grounds together is known to make some devices squeal regardless of any specific input, especially if we're talking about cheap shit like consumer HiFi amplifiers/receivers as opposed to studio equipment.
There's a lot of fibre optic stuff in car entertainment systems, called MOST, because a bit of clear plastic is cheaper than copper and weighs less than copper and i guess resilience to current loops and EMI is nice to have too, i mean you know what happens when you start the engine.

TOSLINK simply being optical S/PDIF also makes it trivial to convert one to the other. Back in the 90s, I used the Mini-TOSLINK input of a MiniDisc portable to record from a digital satellite radio receiver. This only had an electrical S/PDIF output. As far as I remember, the converter I built was not much more than a few connectors, an LED, a transistor and a power supply.

The professional equivalent to S/PDIF (same digital protocol) is AES3 which is typically transmitted over a balanced, twisted pair cable with XLR connectors.

The Sony discman I bought in Osaka in 2001 has a mini-Toslink port. It was most commonly used back then to connect to an MD player to make copies of CDs.

I had a PC sound card with mini toslink, the adapters ( to normal toslink ) were plastic and I broke 1, it was during research into replacements I found how common they were

The mini-Toslinks were fairly common in a couple generations of Apple laptops, at least the Macbook Pros in the era where they had Minidisplay Ports (that didn't pass audio). It was the only way to get video and digital audio to a TV from one of these without using dongles or an external sound processor. I'll have to look, but it's possible the Core 2 Duo era of Mac Minis had these too, and I'm reasonably sure those had DVI video only, not MDP or HDMI.

There's a benefit to optical cables over copper - you don't get ground loops.
TOSlink is essentially a stretched opto isolator. So all your audio stuff is electrically isolated. Not much difference for digital signals but if you have a mix of analogue and digital it might be helpful.
Also LEDs, photodiodes and plastic fibre optic cables are all pretty cheap. Add in the fact it seems like an open standard with no licensing fees and I can see why it took off.

When I wanted to connect my TV wired to my internet connection, I found POF (plastic optical fibre) and it works really well. You cut the fibre to length yourself and poke it into the converters. I've since replaced it with classic optical fibre but it was cool to play with.

Another fun video! A lot of sound cards for PCs supported toslink as well, but weren't allowed (for whatever reason) to output surround sound. Back when Creative had their own sound effects system (EAX) I don't believe it allowed you to send that over toslink either. I've also had numerous problems with PS4 surround being supported on receivers, for whatever reason I cannot fathom. Cheaper TVs with optical out likewise supported stereo only. It was cool that some laptops, including some macbooks in the 00's and early 10's had combined optical/stereo jacks.
HDMI just ended up being such a simpler and more user friendly solution. And the added benefit of only needing a single cable for both audio and video was such a boon. Especially if you were running a lot of systems to your receiver.
Just wanted to share some personal input/experiences with toslink. It was cool as hell though.

I had a PCMCIA card Soundblaster Audigy that had the hybrid optical and analog headphone jack that doubled as a mini-Toslink jack as well. That was a really sweet feature that I utilized.

I honestly love Toslink. I use it for gaming with my Astro MixAmp and for whatever reason it sounds waaay cleaner than USB or 3.5 mm audio jack. I do wish more hardware used fiber optic cables.

"Handy Dandy Movie Input". Thank you, I laughed probably more than I should have.

Don't forget about those fiber optic trees everyone had in the 90s.
I assumed the keying of the TOSLINK cable was to keep things that aren't a TOSLINK cable from being plugged in.

Love Toslink. The cable can be very thin, compared to normal copper cables (only as thick as ~mobile phone charger cable), can be at least 10-20m long, is really cheap (from ~€0.5 per meter), and has been 100% reliable in my ~10 year use (PC to audio receiver), offering perfect quality. It is a shame it was/is not used more widely.

Great video. Fun fact: every Mac with a 3.5mm headphone jack and all airport express devices going back to late G4 PowerBooks has secretly also possessed the ability to output digital audio over mini toslink.

use a badly insulated wire cable for a relatively long distance (say 5 to 10 meters) and you are likely to get a static humming noise from the cable wich will be there regardless of if you are playing music through it or not.
toslink doesnt have that disadvantage
you can also send surround sound through toslink

Since you mentioned the minidisc player twice, do you plan on covering the standard? There's quite the resurgence of the format within the last 3 years thanks to artists in the Vaporwave genre. Thoughts?

one positive ive noticed while using fiber optics for audio is that my pc was making noise that was going though the cables and into my speakers and after using fibre optics it wasnt making that noise anymore. im still using fiber optic cables in my surround setup for my pc

"It's pretty impressive that a digital standard introduced in 1983 is still quite common in consumer A/V equipment" MIDI's that old too. The classics just don't quit.

For the longest while, I've used purely analog even with a dedicated audio processor either in or hooked up to my computer. That said, my Sound Blaser Z has TOSLink capability, and my X3 external DAC has TOSLink output capability (which apparently lets it use a Dolby Digital Live encoder for "immersive surround sound")
But never used it, only mildly considered it from time to time (which would have necessitated replacing my computer speakers, which are quite fine)

Big plus of Toslink is hum prevention because it galvanic separates ground loops. Btw, I regulary used Minitoslink to record on my mobile minidisk player.

The Mac Mini I bought in 2008 had mini Toslink in/out. I actually used that with a Mindprint DI-port AD/DA converter.

The silly thing is that I'm currently using TOSLINK because the cable wasn't particularly pricey and it actually freed up the S/PDIF port on my sound setup (which I sometimes use for when people want to bring music that isn't available via streaming).
Also, it's funny that you should bring up power surges and separation of devices; I once lived in an apartment where ground didn't work so I would get a "buzzing" from the metal body of my laptop. I took the laptop off of its power supply expecting it to stop, but nope it continued. Turns out that at that point I was being shocked through the external monitor that was plugged into the surge protector and the external monitor was plugged into the laptop. Kind of a niche problem, but you'd be amazed how often places do a poor job wiring up outlets.
I think that if they really wanted to update TOSLINK they could probably do it by adding multiplexing using different wavelengths of light the way that they do it with other types of fiber so that it could have bi-directional communication as well as more throughput. To be backwards compatible all they'd need to do is have a newer device try to send a "handshake" signal on one of the newer wavelengths; older devices wouldn't send it or wouldn't "see" it so it'd probably wouldn't be too much trouble to get the newer devices to automatically treat a connection as the older connection type if the "handshake" wasn't successful.

This is actually a good design and idk why it didn't blow up. Good job toshiba

Pointless personal fact: my father was part of Bell Canada's fiber optic conversion in the 80s and 90s so my childhood was FULL of cheap copper wire with colourful coatings to make crafts with, since there was just so frigging much of it.

Just somewhat recently Toslink\SPDIF has started to become a thing in car audio. I think mostly due too effective isolation of ground loops that are very common in car audio installs that cause all kinds of noise in the final amplified analog line level signals. I just recently purchased a car audio head unit that has optical\coaxial Toslink\SPDIF jacks and it appears that some current higher end model line of car stereo amplifiers are appearing with Toslink\coax jacks. This fact is actually what led me to find this video. I'm guessing this is being used in car audio because 1) it works, and 2) has very little cost to implement. I am guessing no licensing costs that car audio manufacturers would have to pass along to consumers if they were to license the new technologies like HDMI.

Ah mini toslink, I love it's inclusion on the chromecast audio, I use it, it's neat that it has digital out, but it just feels so out of era.
Also on another toslink related story, I work for a electronics retailer, you get funny coincidences where lots of people want the same seldom sold product on the same day, projectors are a big one but I've always put that down to some sort of market trend where it's investment pitching season or something. But one time there was a week long run on toslink cables, several people every day where you'd usually be lucky to sell one a month. By the Friday we ran out, and when I would tell the customers we were out of stock they were equally baffled "why would you sell out, it's a decades old obsolete cable, I only need one for an obscurely random reason". To this day it baffles me, I've come to believe that coincidence is a thing in and of itself for its own reason, some sort of base universal nature of probability that builds up into things like runs on toslink cables.

I first encountered TOSLINK when I got my first MD recorder in 1995 when I was in Hong Kong. Of course, the portable MD recorder only had a min-TOSLINK output, so I made sure to purchase the appropriate TOSLINK to mini-TOSLINK cable at the same store in HK. And luckily the Sony LD player I owned at the time, had a TOSLINK output (but no coaxial SPDIF output oddly enough--you'd think Sony would want to support THEIR OWN DIGITAL INTERFACE ON THEIR OWN EQUIPMENT!!) I made sooooooo many MD recordings through that setup. Still have many of them and they play perfectly to this day.
Other digital recording portables went with mini-TOSLINK as well like DAT portables and Digital Compact Cassettes (yes, even Philips went with TOSLINK over their own SPDIF ON THEIR OWN DIGITAL RECORDING MEDIUM!!)
One of the best advantages of TOSLINK at least to LD player owners back in the day was that since most LD players supported TOSLINK outputs over coaxial, and with the highly overengineered and poorly executed way that AC-3 was implemented on Laserdisc, DTS Surround was possible through just that connection. All you needed was a DTS compatible receiver and your TOSLINK output from your LD player, and you were good to go! Didn't need a dedicated AC-3 output, RF demodulator and AC-3 compatible receiver (or if you had the big bucks, a receiver with a built-in RF demodulator) to get Dolby Digital Surround from your LDs.
I'll never forget my friend's face when I brought my big ol' clunky LD player to his house along with "The Crow" on DTS LD to compare the audio from his Dolby Digital DVD of the same movie. The DTS LD was waaaaaaaay better! We actually watched the movie with the two movies synched up on each player--video from the DVD (because the DVD did look better since the picture on that Sony LD player was starting to go bad--that's another can of worms I don't want to open here) and audio from the LD!!
Even then some people prefer with just TOSLINK from your LD player, you could still enjoy the matrix Dolby Surround soundtrack that every Dolby Digital LD had on its digital tracks if you didn't have an AC-3 compatible LD player and RF demodulator. I know some who even prefer that soundtrack to the AC-3 track since being on the digital tracks of the LD, its bitrate was far higher (1441 kbps--same as CD) than the demodulated AC-3 track (384 kbps if I remember correctly.)
Anyways, I think I cluttered up the comments section here enough. Great vid and great info!

Listening to this video's audio via a Toslink connection to avoid hum introduced by computer and audio system being connected to different mains circuits really enhances the experience 🙂

My 21 year old receiver has Toslink, as does the TV I purchased last year. I always assumed that it was somehow the peak in audio quality and always had been. Makes me feel kind of silly for having to order a new cord because my old one was just a few inches too short for my new setup.

My speakers on my 10-year-old TV gave out last year, and I bought a new little speaker for it. The only jack they have in common is a TOSLINK, and it's still working like a charm for me!

I had to use Toslink to connect PC to Soundbar. Yes, you can push it in in multiple rotations. The biggest problem I have with Toslink (main connector) is that you cannot move any of the devices as it does not hold inside.

For me it wasn't so much the cables but adding a power conditioner was a game changer.

Combination jacks are always cool! (When they're built correctly, that is!)
32 channels of audio. Just in case 7.1 isn't enough. :D

I always choose TOSLINK connections over the voltage switching ones. There is no drop in the transmission and detection of a light pulse, while those RCA/Coax cables degrade over time and misread the switching voltages on occasion. This is most notable if any of the components of your sound system synchronize using Bluetooth, like most consumer level subwoofers for soundbars do these days. TOSLINK and optical transmission will pretty much always sync up right to the bluetooth delay, whereas you get a little bit more of a pronounced separation between the voltage switching RCA and the bluetooth connection to the subwoofer or whatever surround wireless setup you might have. It can get a bit disorienting. I highly recommend TOSLINK over RCA connection. Now, if you have direct connection like a jack or even the more and more common USB, it's not as bad. I still just like knowing that the connection speed of the DAC in the sound processor coming from the source is set and locked at "the speed of light".

Fun fact : almost every multi-cab multiplayer arcade machine used TosLink for the communications

One thing that was not mentioned is how much better it isolates channels into the sound system you use. I am using a 2.1 sound bar from monster and when I had 3.5MM To RCA and it wasn't addressing the Sub on the bar. Now it is and the channels dont have an issue of separating the signal left and right and it is much clearer now that the channels are specific and the sub is used. Also no buzzing due to no reference voltage/ground feedback issues.

Pretty common use case is HDMI via fiber it allows thinner cables and a much greater range than the 10m max of the HDMI standard.
As far as I know it is not standardized, but there are quite a few suppliers out there with them.

Toslink got one advantage that was not mentioned (or experienced) - eliminating ground loops
I had serious issues with my computers while running the amplifier on a different plug (probably a different phase circuit or different grounding circuit)
ground loops were able to get into the audio output, even when tried on different amplifiers
one solution was to isolate ground in the plug - but I wanted to have both computers and amplifier grounded
(got ground loops in 3 apartments I was living in, apparently not so rare when having 3-phase power at home)
Toslink is awesome, it has been it on all my laptops, my Minidisk, my workstations
nowadays laptops do not have it, only motherboards
it is capable of 96kHz 24bit stereo at least

12:57 this is why i enjoy going back through your older videos again (yes, they do have a high replayability factor!) clock jitter was something i had to deal with a lot when i was designing, coding, and installing Interactive Voice Response (IVR) and Voicemail (VM) systems 30 years ago. IVR is that "press 1 for this, press 2 for that" thing that everyone hates (including me). yep... i helped develop those prior to going to work for phone companies. and i now wish i never had. so when we are all cussing those, we're all cussing *_me_* by proxy.
getting the timing right at the interface of a computer network and a telephone network can get maddening at times. so your comment about Clock Jitter is very, very, VERY, *_VERY_* accurate. there were a few times that i was forced to take time off of work simply for my mental health. i am not joking or exaggerating.

Long time lurker here and I have to say, using a S/PDIF cable for a computer connection to a surround a/v receiver for audio only is far superior than using a 3.5mm. The noise generated on motherboards and sound cards can be atrocious. I hope it may inspire you to know your entire video was broadcast over S/PIDF to my A/V receiver for my noiseless pleasure. I especially enjoyed the examples of signal degradation and loss. Thanks for the video :)

The amount of data that can be multiplexed and transmitted on a single optical fiber is staggering. I recently took a training class on service provider optical networking equipment. When they covered how to add and drop individual 100Gb circuits using multiple wavelengths, and how you could then merge banks of those multiplexed circuits, the numbers started getting to be incomprehensible. It's truly remarkable stuff.

I used TOSLINK to pipe digital audio to my minidisc player, it had an optical in. It was AWESOME plugging a clear laser cord in to my little square portable player from my optical out on my PC.

Optical Audio has the advantage of ground loop isolation (and RF rejection). However, connecting a TOSLINK only source to vintage analog gear is a PITA, as it requires a DAC/converter adapter. ALSO, if you need, Dolby Digital (ATSC TV audio signal decoding), finding the proper DAC/adapter that works can indeed be hit and miss.

12:10 I once read a article on Japanese audiophiles who have a whole separate power source from another grid. don't know how he achieved it. but essentially his power for his stereo is split from his power for the rest of the house, and this happens outside his house, way up the street. effin crazy yo.

Toslink is a great digital connection protocol, since it’s about as easy as plugging a TRS Jack into a receiver. There is no issue with USB jitter and artifacts, and no issue with installing drivers. Toslink was how I was able to output the digital audio from my Playstion into my high res DAC’s S/PDIF receiver, when there were no USB drivers available to install. It’s a shame many laptops stopped integrating Mini Toslink output ports into their headphone jacks; it was killed off on the MacBook Pro in 2016.

The problem I ran into with an old 5.1 receiver I got years ago is that it didn't support video pass-through from 4K. It works fine with toslink audio, but the hdmi ports became obsolete.

Excellent video! Toshiba also has 'TOSLINK 190' which goes much further/ faster and can be bi-directional.

The fact that the optical connection completely electrically isolates the two connected devices is no joke! At some point I had really irritating problems with connecting some audio devices, there was a clear "hum" that was some kind of ground loop interference. I tested a lot with different grounding settings, and when I finally was able to use a toslink cable, the interference was eliminated. So I would say that in some "bad" grounding related setups the optical connection's electrical insulation property can be a saver!

You might have under estimated the electrical advantage of optical fiber with regard to ground loop and outlets wiring. When the transmitter and the receiver are connecter at a great distance (which is the case in some audio applications) they have different ground level through the building electric wires. Given a conductive cable to transmit data and both ground will be in contract through a different path causing a few volts to travel through. It can lead to device heating up in some cases... Not really significant for recent home, but for large building or really bad wire it can be eventually a safety issue. But the most important difference of course is that it's a lot cooler to go optic isn't?

I've spent alot more on 'upgrades' to my cables, and even a new stand alone dac, to find there was no sound difference. But, yeah, the TOSLINK looks cool.

We used to use optical links as electrical isolators when we had data collection terminals in areas that could be hit by lightning, to minimize the damage to our controllers. I think they worked, but I never had a lightning strike I had to deal with. This was about 40-45 years ago.
Today, the terminals would probably be wireless, solving the problem.