I do most of my listening in a small home office (10 by 14 feet with hardwood floors and a 5 x 9 area rug) on a two channel system.
All of my music is ripped to WMA lossless and played on a Windows XP PC / Windows Media Player 11 to a SilverStone EB01 USB DAC (Burr-Brown PCM2702 DAC) into an Onkyo TX-8211 Stereo Receiver (50 watts per channel) to my Polk RTi8's (which I recently got to replace Polk R50s). I also play music in my living room HT setup via a Roku Soundbridge.
I am fairly happy but feel the Onkyo is the weak link in the system and so am looking at replacing it with either a refurbished Pioneer Elite SX-A6-J Stereo Receiver (50 watts per channel) for $320 or a new Harman Kardon HK 3490 Stereo Receiver (120 watts per channel) for $289 or maybe something else. I very rarely play music loud and like small combo jazz, bluegrass, etc.