Power Uber Alles ?

In a 12x18 room with 86db speakers a 100 watt amp that can double it's power into 4ohms would be sufficient.My former house had a 20x16 living room but was open to the dining room and kitchen and I needed 300 watts for the 89db  speakers to get any dynamics at all.
Now my room is 16x17 and lower powered tube amps give me plenty of power with more efficient speakers.The sound quality is so much better to me-realistic and palpable.If I could have afforded more powerful tube amps back then I certainly would have.The quality is more important to me but $$ make for comprise sometimes.

I demand that my power amp puts out some serious wattage mojo, so instead of a tiny low powered single ended amp, I insist on on the 10wpc (12 with some tubes, but with KT77s it’s supposedly 10) provided by my Dennis Had SE amp for room shaking dynamic sound through a pair of 99db efficient speakers. I may be power crazy...

@erik_squires,
Interesting thread, judging from responses so far, there doesn't appear to be any evident correlation between power and sound quality, per se. In my own example above, the only different element changed was increased power and all other factors stayed the same, but, I mean, really, how often does that ever happen in the real world? When you swap out other amp designs that are more/less powerful, or are partnering them with other speakers, then I guess everything else is changing the results of the comparison, it would seem. It's a wash then??

I wouldn't let ebm get to you too bad. Everything you said in your rebuttal to him is true (and I hope would be evident), but the ebm I know has been pretty consistent...I think of him as just our resident 'equal opportunity' hit--and-run 'slammer', lol.

Cheers.

The OPs question is about power and quality.
With respect to power, in my world, you need to have enough power for whatever speakers you choose, to play whatever music you enjoy, at whatever sound pressure levels meet your expectations for realistic dynamics.  Anything less and you are unlikely to be satisfied with the amount of power, in the long term.
The quality part of the question is both objective with respect to the quality of power (i.e., low distortion and minimal frequency variations), as well as subjective with respect to listening preferences.  
So, the answer is to purchase amplifier(s) with enough power to cleanly (i.e., without distortion and frequency aberrations) drive your speakers to satisfying (continuous and peak)  sound pressure levels.
Musical Fidelity previously published a SPL vs. amp power vs. speaker guide.  I could not find it on their current website but below is a link to a forum thread about "moving from a 150 watt amp to a 400 watt amp"  where @bruce_weiland posts the Musical Fidelity info from their 2009 website (see post dated 3-26-18 at 5:14pm) and immediately following @almarg provides additional useful comments on the subject.
https://forum.audiogon.com/discussions/what-does-moving-from-a-150-watt-amp-to-a-400-watt-amp-get-you