Wondering...direct digital out on a computer?

I've been wondering about this for a while, and the Sndrox thread got me wondering again...

So, I have a cheap USB DAC on my laptop. But I know it doesn’t get a raw PCM from the computer because I can EQ the signal and adjust the volume with iTunes even if I’m using iTunes to play a CD rather than a file. That implies to me that the software is messing with the signal prior to digital output. Even if I turn EQ off in iTunes, the volume controls will still attenuate the volume throught the USB output. It IS as digital signal exiting the USB port, right? If I was after sonic perfection I’d want the signal passed directly to the DAC. I know a CD player with a digital out would do this.

Since you need software analogous to iTunes to listen to files on your computer. Is it possible to get an unadulterated digital output?

If you have the eq/effects turned off and the iTunes volume all the way up and have the sound device manager set up for digital output only and at 44kHz/16-bit it should be no different than using a CD transport.

I set up my device manager to output 48kHz/24-bit so I can play PCM concert DVDs without down rez-ing (in most cases). I can bump that up to 96kHz if I want but then the receiver I'm using with the PC locks into stereo direct mode and I like to employ the sub. I don't hear any difference with CDs, wavs, or lossless files with it at 48/24 but it doesn't seem to slow the PC down any so why lower it to CD spec?

Thanks, Slosh...it's that "should" part. (not that I'd notice sonic perfection if it happened).

...sound device manager...

This could be one of those areas where Mac OS X gives less flexibility. With my stock powerbook. I can chose USB output through the system prefs, but there's no further management (44kHz/16 etc.) beyond volume at the system level. Maybe this is something OS10.4 lets you do...I'm still 10.3.