High power amp, does it matter at low volumes?

I am so blown away by the thoughtful and intelligent comments.  I just subscribed to Audiogon for the purpose of posting this question, and I am very glad I did.

I still have to download the test tone, per 'retiredaudioguy' and put my VOM as suggested. 

'mrdecibel' hit the nail on the head. I was lucky enough to have a wife who supported my hobby / desire and who was tired of me taking her into stereo shops, that when we walked into a shop with the B&W 802's she said "Buy em".  It was hard to say No.  After 12 -14 years of ownership, I still like them. The L 532H and L326S are a great combination, and do work well. 

I have the opportunity to buy a McIntosh 426, new, dealer authorized store, demo unit, Black Friday sale.  450 wpc.

I am not sure anymore that it will make a big difference?

For about the same money, I can get new Bryston 7b3 mono amps, 600 wpc.  or Bryston 14b3 stereo amp, also 600 wpc. 

Pass Labs, X250.8 is also in my price range, on the high end.. some Class A, 250 wpc. 

I believe 'retiredaudioguy' is likely right, don't spend money on more power, get more quality. 

Christmas is coming, and then next year is coming, and guess what, I am not in a rush. I am likely driving 2 1/2 hours tomorrow to hear the McIntosh 462.  The joys of living away from big cities.  The closest stereo shop is literally 2 1/2 hours away.

@robeffy IME, although McIntosh, as Levinson, has always worked well with B&W, these two brands (power amps in this case), sound nothing alike...Based on the autoformer design used in the output stage of the 462, which is a Mac "thing" with solid state(output transformers dominate in tube amps, with a few exceptions of OTL), they have a sound that many prefer, and many who do not. When listening to the 462, hopefully it will be through a set of B&W models, close to yours. The best thing you can do, is pay to borrow/rent one, for a week, in your system, if you even need that much time with it to decide. It will be yay or nay. That is the way it is, and everyone on this site, knows it. My best, MrD.

My understanding is that the most important amplifier parameter (apart from distortion, maximum power to avoid clipping which is not important at low volumes) is damping factor: with a high damping factor the response becomes tighter (less "bouncing"). Typically, high damping factor needs a high power amplfier (but it's not a 1:1 relationship!)

@carlosezarate  Damping factor has little to do with the performance of an amplifier.  

Please clarify. Your statement does not do so.