The MX1200 is an audio amplifier made by HH ELECTRONICS in the 80’s which is capable of producing 1200 Watts of power at 8 Ohm Brigde loads. At stereo load this amp produces 380 Watts of power.
Its using 5 pair of MOSFET as final transistor amplifier. It using 2SK576 and 2SJ56 which has maximum dissipation 125 Watts ( DATASHEETS ). It means that the amplifier can make 625 Watts per channel or 1250 Watts when its bridged mode.
The edited schematic diagram are below:
The Power Amplifier only has 3 amplification levels, they are Pre-amplifier, voltage amplifier section and last current switch as the final amplifier.
In the schematic above, it appears that the final output transistors are using 5 pairs. Even thougt the picture shown only 2.
With 90 VDC supply, the power amplifier is possible to deliver 1450 Watt Output. But the amplifier schematic are design for 1200 Maximum output.