Just a quick 'extra' - I had a look at the user manual (which rather nicely gives a schematic) - why is it called a 'hybrid' amplifier?, as there's nothing hybrid about it?.
Circuit wise, it's quite crude and simple - and obviously can provide nowhere near it's claimed output.
From the power supply voltages (assuming little or no voltage drop) it 'should' be able to provide 150W per channel to 8 ohms, or 300W per channel to 4 ohms. However, even at that, I doubt it would survive long as it only uses single pairs of output transistors, which are rated at only 150W maximum dissipation.
The fine old 2N3055 was rated at 115W, and was good for 50/60W output amplifiers - but if pushed to 100W reliability would be very poor, so usually two were used in parallel (so back to 50W each pair).