Newbie question re: USB quality

I think it's ironic that it's argued above that USB done right is awesome...in context of converting it back to S/PDIF :)

To the OP, yeah, two paths - one would be a USB-SPDIF converter from Mac to Oppo (loads of them around now). Another would be to double-down on improving the USB from the Mac with stuff like iFi iUSB, iFi iPurifier, a better USB cable.

It still comes down to what the Oppo seems to do better with. Try to do some comparisons across the different inputs to see if you can detect the baseline preferences it may have between optical, coax and USB.

Bcgator, OK I looked at the Peachtree. It has Toslink, USB,
RCA and BNC coax inputs.

You need to determine which input kind of sounds best as-is,
and double-down on improving that.

From the PC, are you running JRiver in WASAPI/ASIO mode? Do
that first to setup bitperfect playback over USB direct.

Then see if you can compare that vs coax, say using a CDP or
DVD or Blu-Ray player with coaxial out.

On paper, the best inputs are likely USB or BNC.

To improve USB, consider the iFi iUSB device and better USB
cables (I use the iUSB with their Mercury and Gemini
cables).

One of the best BNC S/PDIF converters is meant to be the
Audiophileo, but it's not cheap. You should not buy a PCI-E
(sound) card. You want the conversion done outside the
computer for power noise reasons. Even if going S/PDIF, the
iFi iUSB is still a beneficial device, so maybe I'd start
there and you can get it from several places with
return/refund guarantees.

Can't agree with Cerrot here, the juli@ is fine but it's embedded in the PC, via the motherboard, and all the crap that entails. I used to use a modded EMU1212M and the sound was good for its day but USB and SPDIF converters supercede it.

Regardless, if we've established that the Peachtree's USB is good, then again, Bcgator, look at optimizing that. And if you're happy with the sound you already have, why spend anymore!