The busbar wiring in the middle and the flying diodes over the caps in the lower left corner take me back -
Back in the early 70's when I was in school and building a TV station, part of it was hand-building some 24 Vdc, 10 A linear power supplies on 3U and 4 U rack panels (public TV station, no money to buy commercial units). Control transformer, big black diamond bridge, and large "computer grade" electrolytic caps. The wiring was open frame using #10 bus bar in what we called "refinery wiring" - exactly as in this amp. Lovely.
ak