Here is a way I have found to get very nice sound from your computer. After reading many posts on several forums it seem to me that a firewire interface seems to be the optimum. I started seeing a lot of buzz about a new m-audio product, the profire 610. So I went to my local musical instrument store, talked to the guys there and I ended up buying one.
WOW is what I have to say about this product. It playes files upto 192/24. It records (built in mic preamps,/phantom power), it is a 6 channel input (4 analog, 2 S/PDIF), 10 channel output(8 analog, 2 S/PDIF). Also MIDI in/out! It has a volume control knob! 2- 1/4" headphone jacks, each with its own volume control. It has balanced inputs, balanced outputs. If your computer has 6wire firewire it is powered off the bus. A nice laptop like power supply is included if you have 4wire firewire. 4 wire and 6wire cables are included. The outputs are 1/4" TRS jacks. I bought a couple of 1/4" TRS to XLR cables to hook it up to my ARC preamp.
The sound I have found to very good! I am loving this thing. It is so flexible through its software. It has provided me with many hours of fun trying different configurations and great listening.
I have a small Toshiba laptop that I have started using to stream internet radio (sounds very nice), the sound from DVDs is spectacular. I have purchased HD music from the net and, again, WOW!
Last night an idea! (my wife usually gets out her hardhat and ear plugs when this happens) I fed the analog outputs from my ARC CD3mkII player (this unit has wonderful sound)to the 610 and recorded it at 96/24. A new kind of upsampling! The sound is awesome (running out of superlatives). I paid $399 +tax and cost of cables, about $500 total. I am really surprised by the quality of this unit, It is built like a tank, heavy steel case, and really nice sound. It comes with software that you can use to record. I love it!