I've not had a lot of experience with separate components before the Emotiva setup, but the speakers are certainly not hurting for power in the least. In fact, the XPA-2 is probably overkill.

For reference, the Emotiva components include (1) XPA-2 amplifier, (2) USP-1 preamp, (3) ERC-2 cd-player. and (4) UMC-1 processor for movies. I still have my trusty Oppo BDP-80 for blu-ray.

The XPA-2 with USP-1 is dead silent--no buzzing or any other noticeable noise. Switching to the UMC-1 (using the HT bypass of the USP-1) adds a bit of noise, but it's not overly noticeable.

As for the sound, well these are the Sierra Towers after all I prefer a bit heavier bass, and my room is not very obliging, so I splurged for two Rythmik F-12 subs. Two subs definitely seem to help produce more even low bass output (actually, it was kind of weird when I had just one sub connected as I played a song containing heavy bass which caused an uncomfortable pressure feeling in my ears. When I incorporated the second sub, the strange ear-pressure thing vanished).

I did add attenuators to the amp output as the volume step increases with the USP-1 are a bit much. At some point, I may switch to the XSP-1 which doesn't have this shortcoming.

Overall, the system sounds 10X better than my former speakers with standard home theater receiver. The problem now is that I am itching to add a Sierra Horizon, but that would require purchasing an additional amp... and then I would feel obligated to get surround speakers. It's a slippery slope.