USB vs s/pdif

I'm pretty sure that the USB input on the Wyred DAC1 is adaptive, not asynchronous. Implementations of adaptive USB vary widely in terms of SQ, largely as a consequence of jitter. I haven't heard the USB implementation on the DAC1, but it wouldn't surprise me if it's less than stellar.

The Wyred DAC2, however, has an asynchronous USB input. I have compared its USB input with its S/PDIF input and I found them very, very close in SQ. (I don't own the DAC2, but I borrowed it from a friend to listen to in my system).

FWIW, I believe that Wyred will upgrade the DAC1's USB input to asynchronous (like the DAC2) for a charge.

Bryon

I keep trying USB interfaces on DACs and I just haven't heard one I think is very good. I have heard the USB interface on a Wyred4Sound DAC2 and compared it to spdif and toslink. If I owned that DAC I wouldn't use the USB interface, just like I don't use the one on my own DAC.

I'm using USB with a moon 100d which is asynchronous. Moving to a decent USB cable made a lot of difference. Tried toslink, which was OK, but I prefer the USB route.

My experience with USB was always a letdown until the async USB of the W4S DAC2 I'm currently enjoying.
In my opinion, unless asynchronous, USB is not up to par with S/PDIF. In asynchronous version, the cable stops making a difference, as no timing info is passed from the transport to the DAC.
I'm sure other posters will have different opinions, though, as usual.