Old Amps that can still Kick Butt

Not being a believer that time necessarily = progress, I would like to offer the following example of a sonic gem that has transcended time and can totally kick butt in a modern milieu:

The Robertson 4010. I got one of these about two years ago because it was in immaculate condition, the price was so low and I was inquisitive. I hooked it up and let it warm up for a couple of days. OMG this thing was in the super amp league: Transparency to die for, slam that you couldn‘t‘ believe for for a 50W amp.. Peter Moncrieffe wasn‘t wrong in his review of this amp: this thing is in the Sterreophile Class A component category hands down. Even after all these years.

What amps have you encountered that have defied time and can still kick butt today?

Back in the mid-1970's I was the second owner of a mint-condition McIntosh MC225 tube amplifier.  I didn't make that much money back then and was offered a huge price for the amp and sold it.  I wish I had that amp today!
I bought my VAC PA 100 100 tube amp and ARC LS15 tube pre amp back in 1995 and they are still going strong with no issues
I just replace the tubes on both units as l thought it's probably time to replace them
Just recently l bought a used Spectron musical MK ll class D amp to drive my Maggie's and l love that old amp and how it  
makes the Maggie's beg for mercy!
Any amp from David Belles still sound excellent and can show many amps the door