Regalma1 -
I own a USB DAC, and it rocks, however, that's not totally true. I need to follow up on my last comments because I mis-stated something major in it. When I last tested the CD transport against the DAC, I had the DAC running from the USB input and not the glass toslinks. In theory, the direct USB should have sounded better, but in my setup it does not. It has taken a LOT of experimenting to get here, so I will share my experience with others and hopefully save them a lot of time.
Get a Trends UD-10 (USB to SPDIF converter) or similar device. Then upgrade the power to a linear power supply (absolutely necessary). Run a glass toslink from the USB converter to a jitter reduction unit (I use a MSB digital director). Then run glass to the DAC. With the digital director, I can have up to 6 digital sources that automatically switch when they get a signal. This way I could play back the CD transport and the computer at the same time and flip between the two, playing the same song at the same time. I could not tell a difference between the two! The computer sounds just as good now. I swear by the MSB digital director... going through that opens the soundstage and bass response that was lacking compared to the CD transport against the USB input to the DAC. And I'm talking the difference between sitting and listening to music for hours instead of just turning it off. It's what puts the music right into that place where it comes into the room with you and is so involving. That's what I need when I listen!
My girlfriend and other friends have also commented on it and agreed that going through the jitter reduction sounds better than direct USB, and they are not as freakish about sound as I am.
Yes, this may just be my system. Maybe Audioengr's equipment does this without using a seperate re-clocker (like the MSB I use) or just clocks it right in the first place. But what I'm trying to get at is that the direct USB doesn't always mean it's better!
Rock on!
Ben