Last night I performed a modest experiment in my living room. I have an Yamaha RX-V795a home theater receiver rated at 85 watts/channel powering my Paradigm Reference Studio 40's.
I moved my Rotel RB-981 (rated 130 w/channel) upstairs and gave it a go on the same system, running off my Yammie's pre-outs in 2-channel stereo.

The Rotel sounded SIGNIFICANTLY better at all volumes than my Yammie. And not just the warm sound compared to my Yammie's brightness (which I actually enjoy), but better soundstage, everything just sounded cleaner, and bigger. I'm probably not using the right words here, but even my fiancee had no problem telling the difference. After about an hour and a half or so I couldn't find one song that didn't sound better running off the Rotel.

Why is it that my Rotel burned my Yammie? We used 16 guage speaker wire from the same roll, the same speakers etc. I didn't take advantage of the extra power the Rotel offers and even had my SPL meter to make sure the volumes were the same. Are A/V receivers just too busy inside to turn out as clean and full of a sound as an amplifier?
Are power amps just an all around better idea for stereo playback? I've always thought speakers had more of an impact on sound, am I wrong here?
Is my Yammie that bad, or my Rotel that good?
I'd love a technical explanation that would explain to me why exactly my separate amplifier outperformed my receiver.
Sorry for ranting, appreciate any comments.