Wonderful & awe-SOME!
By your "handle" one can assume you are a Mesa Fan!

The 400 could well be at least one of the KINGS of amps. And Diesel Cabs... See rant below:
I'll just say that I bought a Walk-About when they first came out, from Mesa-HollyWood in my old SoCal 'hood.
Also ordered a 4-Ohm PH212 in beautiful Wine -like colored tolex.
Damn that was a great cab.
Both, alas, sold!
But before that:
I saw this there: (Stock photo)
View attachment 1174932
It was the Store Demo, & I grabbed it up, had never seen anything like it.
Granted it is no Tower of Power, as a matter of fact, it is a little squat mofo.
I used to also employ it on top of a Diesel 15. (sold!) That was an amazing cab
Cons: Li'l squat mofo; heavy s.o.b.
Pros: 2x10 EVM Black Widows, Sounds like the Heavens. Ya know' tubes.
I just recently had serviced,(needed deep cleaning) sounds like new!
Sorry for the hijack, should be in Thread: Are HEAVY SQUAT AMPS HISTORY?