I could tell a world of difference in sound between the only 2 receivers I've ever used. Both in 2 channel stereo mode.
1) Sony STR-DH500 $160
2) Pioneer VSX-21TXH. $630
Edit: The Sony just had a lot less power and couldn't drive the speakers nearly as good as the Pioneer can. After swapping receivers, I could hear a lot more bass coming from the M22's.
Did you hear a difference at all listening levels or just high volume? Also, I wonder if the different (presumably better) DAC in the Pioneer is contributing as well...
