PC audio with USB DAC

Some thoughts:
If all your music is on your hard drive, and you are working on your laptop while playing music through your USB DAC, I suggest you get the music off of your hard drive and onto an external drive, because your hard disc gets hit a lot as you work on stuff, and this gets in the way of the audio signal.
External drive should use a different bus than your USB DAC, as I posted above.
iTunes does not load music into RAM and playback from RAM, it hits the drive where the music is stored (I think). JRiver has a check-box to playback music from memory, try checking this box to get rid of ticks and pops. Also adjust the buffering from the default 6 seconds to 10 or 20 seconds, if you can stand it. This is all under tools->options->settings.
Hearing a difference between lossless and lossy file formats is highly dependent on the quality of compression, the signal path/settings in the computer, and the quality of the system you are using, there are many, many variables.
I doubt you need special drivers, Windows 7 supports audio output up to 24bits/96kHz. If you get into some 24/192 or 24/384 high res files, from HD Tracks and the like, you might need special drivers, depending upon your DAC.
One more thing, at the risk of angering the budget audio gods, I have found that the USB cable counts. Big time. I have heard a vast difference in sound quality between USB cables in my system, I suggest Pangea PC, they are cheap, $25 for 0.5m at Audio Advisor, silver plated copper cable. You can return it if you don't hear an improvement over stock USB.
Sheesh this post is getting long, sorry about that. JRiver will also auto-detect the bit rate and sampling rate of your music track, and will adjust its output to match. iTunes will not do this. If you are only running 16/44.1 music rips, do not allow Windows to up-sample that output. Let your DAC do it, and set windows to output 16/44.1, if your DAC will take it. You want the computer doing as little as possible to the audio signal, turn off all processing.

Some other thoughts:

1) USB cable is important, but never buy a digital cable of ANY type less than 1.5m in length.

2) Sonos is a great product functionally, but the audio quality is poor. Needs reclocking, which can be added at more expense. Good 1.5m S/PDIF cable is critical.

3) Never use iTunes on PC, only on Mac, and even then make it sound better using several tools such as Amarra, Audirvana, Pure Music etc.. Jriver or Foobar2000 are good choices and can be improved by adding Jplay.

4) If you are using an inexpensive preamp or receiver, this will likely mask the differences between audio formats, data compression and sample-rates. Best to eliminate it or replace with a passive transformer linestage.

Steve N.
Empirical Audio

I knew that applied for digital coax, was not sure about USB, Steve. I have had recommendations for short-as-possible USB cable from other designers of USB/SPDIF converters. I've skimmed your white paper.

Steve N.,

Reading your summary above, the only items that is not clear to me is the digital cable length. I am having difficulty seeing where a 1.5M cable is more efficient then a .5 M cable in delivery digital content. I am open to the argument but --- I just cannot see where electrons traveling 10M is better then .5M for quality. I am not an audio expert by any means, and am open to a solid justification.

Only other comment -- Fidelizer vs. Foobar or JRiver on a PC -- your thoughts?

Thanks!

Sbleam - the longer cable is required for good performance of ANY digital cable, USB, S/PDIF, Firewire or I2S.

The length requirement has to do with signal reflections, a digital-specific phenomena and issue. Read this white-paper for an analysis:

http://www.positive-feedback.com/Issue14/spdif.htm

This has been independently verified through AB/X tests by UHF magazine in Canada.

Now if the cable is less than 8 inches, this is also good, but not very practical.

Steve N.
Empirical Audio