Computer Audio : Empirical Audio

Rip to WAV or AIFF files if possible
Try Upsampling 44.1 files to 24/96 using S/W programs: SRC, iTunes, R8Brain or Adobe Audition - Wave Editor on Mac (Instructions are on the Empirical Audio audiocircle.com forum)
Avoid ripping to ALAC or other compressed formats
Avoid using iTunes or WMP on a PC for audio playback
Using iTunes by itself on Mac compromises sound quality and resamples files unless you specify sample-rate. Use Amarra or Audirvana on Mac. (More info on how to setup Amarra)
Set 64-bit mode on PC or Mac for better sound quality.
If using a PC with XP, always bypass KMIXER using Kernal Streaming. If Vista or Win7, use WASAPI:
http://www.foobar2000.org/components/view/foo_out_wasapi
http://msdn.microsoft.com/en-us/library/dd371455(VS.85).aspx

Mac Mini has the least problematic USB ports.
Recent PC Laptops are recommended, particularly those with ungrounded power cords. We have had good luck with Toshiba,HP, Macbook and Mac Mini. Not so good with Dell.
If you are using USB output to one of our products, we recommend that you try more than one USB port on the computer. They are often not equal. The latency or time it takes to service them varies even on the same computer. Some are even USB 1.1 and not USB 2.0 compliant.
Dedicate the Laptop to music playback if you are using USB. Using the computer for lots of other tasks can cause conflicts, increase latency and cause popping in the audio.
If you are using USB for audio streaming, do not attach ANY other USB devices to the computer, even a mouse and particularly not USB disks.
Remove or stop all unnecessary tasks, even screen-savers and virus scanners.
Set the player to have the highest priority.
PCs with faster processors work better, minimum 1.5GHz
PC needs 4GB RAM minimum, preferably 16GB
For Mac, 4GB is minimum RAM

The best ripper we have found for PC (the best overall) is dbpoweramp professional with Accurate-Rip enabled:
http://www.dbpoweramp.com/dmc.htm

For Mac, we recommend XLD for ripping (also enable Accurate-Rip):
http://tmkk.pv.land.to/xld/index_e.html

Also worth trying is MAX:
http://sbooth.org/

For PC driving USB, try Audirvana. For Mac driving USB, use Amarra or Audirvana.

For PC or Mac driving Ethernet or WIFI, use Linn Kinsky/Minimserver/BubbleUPnP.

For Mac, the best upsampler is Wave Editor (uses Izotope code):
http://www.audiofile-engineering.com/waveeditor/

Empirical Audio