Watts! How many do we need?

Also consider clipping for tubes and SS is very different. (I'm running SS now but owned 3 tube amps and use a tube DAC now so I'm not trying to pick a side here)

Part of the reason we like tubes, is the distortion, which increases as they get overdriven, and is obviously part of the design/intent in tube guitar amps. 

It's Jazz Sunday in our house today, and something else I thought of as I play both analogue and digital albums, is the wide variation of recording levels. It's nice to have (virtually) unlimited reserves of clean power for those lower level recordings.

Lastly, I don't understand this.

with far fewer headaches and travails than an amateur attempting to joust with walls of drivers and 600 wpc

You don't need walls of drivers and the only jousting with 600wpc is financial/spouse approval.

I don't think you need that many watts to drive most speakers.  I was using a 10 watt class A amp to drive a pair of Super Tablettes (86 db I think) in a 13x14 listening room with zero issues.  So then I thought, "What the hell!" and put in my 2A3 integrated amp.  Still no issues and the speakers sound great.

Maybe my musical choice isn't demanding?  I normally don't listen above 85db or so in volume.

In the past I would have been afraid to try this combo in fear I might damage something.  But I guess as I get older I take all the experts' advice as they really are...an opinion.  And you know what they say about opinions.

This combo works for me.

"You don't need walls of drivers and the only jousting with 600wpc is financial/spouse approval."

My point was that I have seen systems so expensive, so complicated and striving for so much power and scale that they become unmanageable for the owner.  They're often difficult to listen to as well.

"I was using a 10 watt class A amp to drive a pair of Super Tablettes (86 db I think) in a 13x14 listening room with zero issues. So then I thought, "What the hell!" and put in my 2A3 integrated amp. Still no issues and the speakers sound great."

ProAcs are rather famously amenable to lower-powered tube amps. My first audio heartthrob was a pair of Studios with the little Cary stereo 300B amp I heard in a shop. I was thrilled a few years later when a friend sold me his Response 2’s. Thirty years on, with one set of replaced drivers and two sets in storage, I’m still enjoying them. ;-) I used 300B amps with them for years but the quest for better bandwidth and slightly more power led me to my current 20 wpc Williamson amps.

Current and output impedance are important as well. Paul from PS Audio gives a good explanation here.