Marantz PM-90

Part of the Philips/Marantz high-time (sound-wise and sales-wise), the PM-90 is one of the three top amplifiers of a constantly upgraded and plethoric lineup which included the PM-80, PM-80a, PM-80aF, PM-88SE, PM-88aSE, PM-95 and PM-99SE - plus a few more export-only variants !

The PM-90 rests on a zinc diecast base and is powered by 2x 250VA current-reversed EI trafos producing clean but hot Class A music (the unused portion of which heats up a 3mm aluminium top plate) or more efficient but ample Class AB power.
The sideburns are diecast aluminium, as in the CD-95 or PM-95, for a 27kg total of educated high-fidelity.

The volume is "active" by balancing the actual input and output levels to lower residual noise at all levels - see the schematic below.
The cascode power stage ends on parallel p-p of bipolars while drivers are MOS-FETs ; one CCNE "noise killer" is inserted in the power amp section's feed and, very Luxman, a Line Phase sensor on the back.

A real PM-90 here ; nudies of others here and here.