Hot Rod Mod of Soundcraftsmen A2801 amplifier I did.
I Re soldiered the boards all contacts from input to output. The only
caps I replaced where the input stage ones with some fast cap Solens I
had from my x-over parts but I did sneak in 4 pieces of pure silver
braided 18 gauge from RCA to Board, A habit of mine.
New rectifier and massive 56,000uf cans plus 10 gauge
copper highly stranded wire all point to point soldiered throughout. I copied the idea from my other amp the Eagle 2, it also has a little bigger cans at 80,000uf but 50 volt rails. This amplifier sat since 1990 never used.
Now it is a 140 watt per channel masterpiece. It stands right there with
the Eagle 2 and seems to have a little more air than the Eagle in the upper tone like with the harp on some Victor Espanola's rips with Yanni live in concert.
The fets were like brand new. no need to replace, and the transformer
looked in great shape, I did not want to have to vertical a toroid replacement. It would have made no audible difference at the output
stage anyway.

There is some great old amps out there that are worth upgrading.