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?

I have a matched pair of Sumo Andromeda II a’s running balanced from and Audio Research pre-amp driving a similarly aged pair of Acoustat 100 hybrid electrostatics that have great slam as well as finesse. MOSFETS and Acoustats are a match made in heaven.   https://www.martindareff.com/Other/HDR-Treated-Images/i-3ZfL6Gq/A
I have the Convergent Audio Technology monoblocs. They are the CAT JL1 Signature edition. They are by far the best amps I have owned. I have owned many amps through the years but nothing comes close to these amps. They were designed in 1994 and blow away anything I have heard. The cool thing is what I paid for them. Because a design is old many people over look them. I hope to keep them forever.
I've had my ARC Classic 60 driving my Thiel CS 3.5's for over 30 years. Superb match and I've never been tempted to change. It's fed with an ARC SP 9 mk III. Never had upgrade-itis other than one change in cables. So happy my dealer helped with this pairing as I get to just enjoy it. Sure, love to hear different things, but system synergy rules! Probably saved me a fortune. At this point, getting concerned with age of caps and what to do about it.
I have a beautiful sounding Conrad Johnson Motif 50 watter  in storage along with a Scott LK150 dual Mono Tube unit needing some TLC that is also a killer sounding amp.My current unit is a late 90's McCormack DNA 1 with a board upgrade It is a solid - open sounding brute I bought when I upgrade to Magnepan's which for those who have them know they  are wonderful but "special needs" speakers