Extra power or cleaner power?

I'm putting a system together and am thinking through some of the factors which might contribute to the overall sound quality. I realize that testing things out as I go is the best way, so I'm asking this question not to get advice about what to do next but to understand how folks understand and weigh these factors.

Let's start with a predicted factor -- the speakers. From the speaker description:

Anticipated speakers: Salk SS 6M
Response +/- 3db — 35Hz - 40kHz
Sensitivity — 90 db
Impedance — 8 ohms
Amplification — 50 watts (or 30wpc, tube amp)
Alignment — Front slot port
Dimensions — 9 W x 20 H x 14 D

Some (atma-sphere, decooney) have suggested on this forum that even a 60 wpc tube would be great for these speakers. So, here's my question —

Assume that I could get a very good 40 wpc tube amp to drive these speakers to sufficient listening levels (85 db at about 10 feet), for my kind of music (jazz, classical), and peaks in my (400 sq ft) listening space.

With these assumptions, the question becomes one of priorities. I could either spend additional dollars to (a) buy a more powerful amp or (b) spend that money on a power regenerator. Also assume that if I do *not* buy a regenerator, I'd still do *something* to improve the power (some kind of improvement but much less expense).

The question is: with those assumptions, what do you think would add more to the sound quality? More power or cleaner power?

Perhaps this is an impossible theoretical question to answer. If so, I'd like to know that, too!

Thanks!