Hey Ravi,
It kind of depends on whether you just run your M80s in stereo only, no subwoofer, and, if you do that, how loud you run them. If the latter scenario, do you currently hear any sounds of strain or congestion using your Denon at loud playback levels?
If not, I doubt very much whether you'd hear any difference at all with a larger 2-channel power amp (using your Denon's pre-outs for the M80s) or even a larger AV receiver.
If, in stereo, your current Denon sounds a bit flabby in the low bass, a larger power amp might yield "tighter" bass, but in your smallish room, I doubt it.
Of course, if you're inclined to experiment with a vacuum-tube amplifier, you might hear quite pronounced differences. What differences you'll hear are quite unpredictable because of the impedance interaction of the M80's impedance curve with the output impedance of the tube amplifier, which is never flat. And whether you'd like or dislike those differences, you'd only find out by trying it. Plus there is the aspect of agreeable musical "clipping" of a tube amplifier, which some listeners like and others do not.
Other aspects of tube amplification that are less agreeable include sometimes audible background hiss and hum, frequency response anomalies that you may like (or find annoying), and deteriorating and changing performance as the tubes age.
Best wishes for the new year. . .
Regards,
