Watts are watts?

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.

Impedance curves don't make a huge difference unless you're using some kind of transformer coupled amp with stupidly high output impedance. Decent direct coupled solid state amps have high damping factors that are pretty much immune to imedance and phase angle in regards to producing a flat response. It's not at all difficult to achieve an output impedance of .05 ohm for a damping factor of 80 which is more than enough to avoid impedance matching issues. The only question is whether the amp can deliver current into low impedance loads and that usually hinges on the loop feedback and degeneration of the outputs. And to be clear, a lot of amps out there claiming not to use feedback are degenerating their parts which is feedback by definition.