Optical cable is made of glass, coaxial cable is made of copper. Fiber optic cable is much better than an copper or metallic based cable- just saw your edit in reference to a blu ray player, I say go with the optical cable. I’ve used one for the last 12years

How about choice C, HDMI.

Correct. HDMI carries audio and video over the same cable. Optical is audio only. Never seen coax on a Blu-ray player.

They all carry 1’s and 0’s so it doesn’t matter

This but to be more specific:
Optical is limited to 20 bits depth in most cases where as coaxial and HDMI have 24 bit depth. Additionally some technologies are encrypted and they are only allowed to run over HDMI. So if you have a 5.1 (or anything more than 2.1) sound system you should use HDMI for audio for movies to get the best support for the various Dolby standards. For music it doesn't matter.

Optical and coax will get you surround (Dolby Digital and DTS and multichannel PCM) but for the formats on Blu-ray such as Dolby True HD and DTS Master audio and now with Dolby Atmos and DTS-X these will only pass over HDMI. So if you receiver has it HDMI is best. Even if a receiver doesn’t support all the formats it saves a cable for now and will be ready when upgraded. Optical is still left there for older support but we’ve seen newer players leave it off and AppleTV and Roku models and other devices are HDMI only now.

S/PIDF has not been limited to 20-bit for a long time - it also can handle 192/24bit just like coaxial, although cheap cables will introduce some errors (which most are not audible and likely you won't even notice). HDMI is definitely a generation ahead though. If you are looking to get the highest fidelity audio, the compressed audio formats Dolby Digital TrueHD and DTS-MA are only possible at their highest fidelity over HDMI. You can use HDMI just for audio, too.

IF you are using DVD-Audio, this uses the highest fidelity audio with almost no compression used at all, so it's already pretty awesome. It's hard to find those discs, but they do sound great

That’s a yes and no. The limit in bitstream doesnt come from the cable but from the N/A chip on either the source or the receiver.
The spidf standard has been extended above 20 bits but it does not guarantee that the device will handle it.

The manufacturers specs should have the format specified in the manual.

Bottom line...those optical/coax digital audio connections are obsolete tech. Everything is all HDMI now, plug one cable in and enjoy.

not entirely correct. my receiver only has hdmi pass through. the audio has to be fed to it via optical. it is old but still going. looking to upgrade eventually.

It sucks when you have a still-good receiver that has become basically obsolete. I pulled my Yamaha RX-V995 out of my system because it has no HDMI at all. But that is a bad-ass receiver that blows away the new one I got as far as power for a 5.1 setup. Admittedly the new one is a cheaper version but it was a bummer to replace the old one which cost quite a bit back in the day (around $1,000). But then again its nice to connect everything up with single HDMI cables (except the old gaming systems).

The RX-V995 is packed away, I'm not sure what to do with it but I can't stand to just trash it, it still works perfectly. All my side systems are powered by retro receivers. And I sure ain't selling it unless someone local wants it, because it weighs a ton and would cost a fortune to ship.

My D/A converter doesn't have an hdmi input, but its conversion stages are way better than my tv, so I, pass sound through SPIDF and video to the TV. You should try both and see which one sounds better. The RX-V995 was a very fine receiver, the odds that it beats your tv D/A converter are quite high.

That's true - That's a distinction between the HDMI standard (1.2, 1.3a, 1.4, 2.0...) and the implementation of it. And that would apply to anything in this conversation

Right, I have thought about that, problem is that the TV doesn't have enough HDMI inputs to handle everything (cable box, xboxone, retropie, kodi pi) so I would need to add in some type of remote-controlled HDMI switcher for the video. Another messy cabling setup.

If you end up getting an HDMI switcher, there are some automatic ones, it will be a cable mess but at least you won't need to add a remote control mess to it !

Audiophile magazines usually say that Optical has a little more Jitter when measured than does Coax. So if you had a choice and the audio quality was of upmost importance, then Coax would be you.

Coax can run a higher data rate, and longer runs, so studios doing crazy high bit rates use it. For a long time optical was stuck at 20 bit resolution, although lately I've see some equipment that has upped it to 24 bits (with compatible devices) and 10m runs.

People having problems with ground loops (like with a Comcast cable box) can break the loop by using Optical to bring the surround sound to their processor.

That problem happens because the cable company has it's "own" ground that can be quite different than your home's ground.