Ways to improve DAC performance???

Been through it already, Steve. I have tried too many. Yours, the berkeley, the ayer and some of the cheap ones (and they sound cheap). USB sucks and its actually finally being found out. Talk on the hardcore computer blogs talk about how USB will be phased out in a few years; within these very forums, listeners are finally comparing the mac/pc/USB/DAC to the Bryston digital player and, guess what? they hear that the bryston blows away a PC set up? why? U S B.
You engineers only embraced it because it was like a belly button. Everybody has one.

...and look at the incredible expense to add a highend usb converter (oxymoron?)? at least $2,000! Just for the converter! A GREAT soundcard is $150. Why are we doing it bassackwards?

One issue with USB is that it sends regular bursts of info like the start of frame packet - "The SOF packet consisting of an 11-bit frame number is sent by the host every 1ms ± 500ns on a full speed bus or every 125 µs ± 0.0625 µs on a high speed bus". If the timing of this shifts or is variable, this could elicit a different & variable reaction from the USB receiver & translate into a different & varying jitter or noise spectrum.

We audiophiles who spend thousands to squeeze out every last bit of performance out of a component are trying to squeeze music out of an USB rock. The interface is grossly flawed for music.

Cerrot - you still didn't answer my question. If you tried one of mine, which one? And what player software and platform did you use? All of this matters.

Steve N.
Empirical Audio

""The SOF packet consisting of an 11-bit frame number is sent by the host every 1ms ± 500ns on a full speed bus or every 125 µs ± 0.0625 µs on a high speed bus". If the timing of this shifts or is variable, this could elicit a different & variable reaction from the USB receiver & translate into a different & varying jitter or noise spectrum."

Certainly possible, but this does not matter. The data is reclocked externally with a free-running clock, eliminating all of the jitter from the USB receiver.

USB and networked interfaces can be virtually identical in performance. They both have buffered packetized data that is slaved from the source computer. They both have a free-running clock that retimes the data. Either one is the optimum way to do audio interfaces.

Steve N.
Empirical Audio