Watts are watts?

IMO, there’s no substitute for class A bias output, whether it be tubes or SS.  Think of a class b amp as a dragster idling at the start line and a class a biased amp reved up to 8K rpm. The flag drops. The idling car driver, then puts the throttle to the floor and can go quite fast, however, the car that was reved up to 8K rpm simply drops the clutch and is gone in a flash.  May be a weird comparison, but the class a amp is always wide open sitting there just waiting for a signal.  It’s very quick.  No pause or sluggishness to reproduce that cymbal, snare crack or bass drum.  You can heat your room with them in the winter, but oh what sound.

Actually I love the analogy, being that I'm a huge NHRA fan!
OTOH, I can't say I've ever experienced "sluggishness" in an amp. I think too many hears of being in the middle of live music has dulled my golden ears.

Great thread.....I recently purchased a set of vintage DQ 10's and am considering taking the plunge into some 'mega wattage'.  To me, they sound amazing with my Yammy SS but I remember still a friends Phase Linear 400 and KLH speakers from the 70's.  Wow......  And great anaolgy by @handymann !

I'm an electronics technician, and on paper watts is watts but according to my listening tests tube watts are more powerful, and for me, I leave it at that.

I have no engineering degree but I understand that speaking of speakers it is an impedance curve, that can be complicated. How do you really match an amp unless you customize it ? Aside from both being built by the same company, like Gryphon or MBL. Trying even dozens of different amps would unlikely get you there, especially if you want a near perfect match.