[DeweyCH]

I know USB isn't the best way to transfer audio in real-time to a DAC, so I'm curious if there's a noticeable improvement in SQ for an existing PC-DAC-Amp setup if you add an "audiophile" sound card and use an optical or coax SPDIF connection instead? DAC in question is a Bifrost 2, so we're comparing a bog-standard USB output going to a Schiit Unison USB input vs. a SPDIF output going either to a coax or an optical input with an AK4113 receiver.

 

[PurpleAngel]

I think USB is preferable, over S/PDIF optical/coaxial, for digital audio.
USB offers Asynchronous transfer (better clock timing), S/PDIF does not.
Using an audiophile sound card's S/PDIF output should not offer any noticeable improvement, in audio quality, over the motherboard's S/PDIF output (normally).

 

[ProtegeManiac]

I know USB isn't the best way to transfer audio in real-time to a DAC...

USB is actually more versatile in terms of data transfer.

SPDIF can't do DSD, for one. I don't even remember if my old SACD player can output anything but the CD layer since I don't even recall if there were even SACD DACs at the time (not even ones bundled with a tank of a transport, but like, they're in two pieces like the Meridian stuff).

...so I'm curious if there's a noticeable improvement in SQ for an existing PC-DAC-Amp setup if you add an "audiophile" sound card and use an optical or coax SPDIF connection instead? DAC in question is a Bifrost 2, so we're comparing a bog-standard USB output going to a Schiit Unison USB input vs. a SPDIF output going either to a coax or an optical input with an AK4113 receiver.

If your USB has noise issues, more so if you can hear the electrical noise despite the computer's cooling system being a computer's cooling system (unless you actually have one of those $800+++ passive cooling cases), and your motherboard doesn't have SPDIF, then the soundcard might be able to help.