Firefox,
I had the same concerns as you about audio quality. I just completed a test of MP3 bitrates and uncompressed Wav files on my primary home music system. Although I probably haven't spent as much on it as many others, I have nice full range tower speakers(Stereophile B), Krell premap, and nice sounding Modwright modded digital sources.

I came to the conclusion that 256CBR was the way to go for me. Although I could tell the difference between 160kbs and 256kbs, I could not easily tell the difference between 256, 320 and uncompressed wav.
YMMV.