Optical usually has a lower max sample rate, USB can go higher, that's the main advantage. Toslink usually you want to set to 96/24 or below, some stuff will do 192 but other stuff won't. Original spec was 48/20 but 96/24 is 100% reliable over it with anything I have used. But it is an issue that you can't play 192/24 native content over most Toslink, you need to downsample. This isn't a problem, but it does mean you can't use exclusive mode in Tidal for example, it will play the 96/24 and below tracks normally but if a 192/24 one comes on you'll just get silence. I guess you could use exclusive mode if you set Tidal to "HiFi", where Tidal downsamples on their side but then you wouldn't get the 96/24 stuff either.
Optical jitter may be worse but I doubt to the point it matters. You won't likely hear any of this stuff, I do not believe personally in Hi-Res, but it's one of the reasons people pick USB over optical. If you have some sort of ground loop or electrical noise issue optical will break the electrical connection and can be cleaner, I have used it in exactly this sort of situation, where if there was ANY copper connection between two devices (even an unrelated one I wasn't using) I'd get noise, but it would go away with the optical. If you have this issue, any of USB, coax SPDIF or analog RCA connections usually create the same problem, optical fixes it.
None of these "issues" with optical are really a problem, it's just some differences that might impact how you use your setup. I largely standardised on 96/24 with Windows shared audio because I was using Toslink, not actually as my primary DAC connection (which was USB) but for a secondary one. So just leaving it at 96/24 was simpler. I don't tend to use exclusive mode anyway as (1) with overears I pretty much always EQ (2) with IEMs I don't but exclusive mode has high risk of blasting your eardrums out at 100% volume, and the Tidal app volume control is very bad, keyboard it jumps in 10% increments and it's much harder to get to the right level with an IEM.
Optical in my experience will also go further, spec is 10m and you can I believe even push that. I had a 5m Toslink cable feeding a DAC that far away and that works flawlessly. While USB Audio, for me, at least on the particular cable I tried it with, wouldn't work over a 3m cable. Cable worked fine for regular USB, but not audio. 2m cable from the same brand worked flawlessly.
Optical jitter may be worse but I doubt to the point it matters. You won't likely hear any of this stuff, I do not believe personally in Hi-Res, but it's one of the reasons people pick USB over optical. If you have some sort of ground loop or electrical noise issue optical will break the electrical connection and can be cleaner, I have used it in exactly this sort of situation, where if there was ANY copper connection between two devices (even an unrelated one I wasn't using) I'd get noise, but it would go away with the optical. If you have this issue, any of USB, coax SPDIF or analog RCA connections usually create the same problem, optical fixes it.
None of these "issues" with optical are really a problem, it's just some differences that might impact how you use your setup. I largely standardised on 96/24 with Windows shared audio because I was using Toslink, not actually as my primary DAC connection (which was USB) but for a secondary one. So just leaving it at 96/24 was simpler. I don't tend to use exclusive mode anyway as (1) with overears I pretty much always EQ (2) with IEMs I don't but exclusive mode has high risk of blasting your eardrums out at 100% volume, and the Tidal app volume control is very bad, keyboard it jumps in 10% increments and it's much harder to get to the right level with an IEM.
Optical in my experience will also go further, spec is 10m and you can I believe even push that. I had a 5m Toslink cable feeding a DAC that far away and that works flawlessly. While USB Audio, for me, at least on the particular cable I tried it with, wouldn't work over a 3m cable. Cable worked fine for regular USB, but not audio. 2m cable from the same brand worked flawlessly.
