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?

The James Bongiorno-designed Sumo Andromeda (200 wpc) is another great amp from the past! 
There are still lots of Dynaco ST-70 and ST-120s in service.  Many with rebuilt driver boards.  I ran a pair of slightly enhanced Dyna 70s for over 25 years, then added the VTA boards.  One was built by the factory in 1961, the other built by my uncle as a kit in 1964.  They still make me listen and smile.  
My Mac 240 of course. But the "the one that got away" for me will always be the Threshold 400A i sold to buy an engagement ring. Worst decision of my HiFi life hands down. I will never make that mistake again...
Mac 2105. Smooth with a lot of weight and authority. There's a reason why they sell for ridiculous prices, although I think the prices are too high.