What is the general scoop on this amp? Thing looks practically brand new...
The Accuphase P-300 is a first generation "super" amp.
A little history.
D. T.N. Williamson developed the first push pull tube amp with negative feedback in 1947.
Harold J. Leak refined it and broke the 0.1% distortion barrier. This basic circuit defined Hi-Fidelity for around 20 years.
Tobey and Dinsdale developed the push pull transistor class B amp in 1961. They sounded awful and were unreliable. There were many examples, but likely none still working.
Peter Walker with D. T.N. Williamson worked to produce a solid state amp with comparable quality to tube amps. The Quad 303 appeared in 1969. This was A/B bias and was 45 watts per channel. It was very reliable due to an underrated triple output stage.
In the early 70s a number of transistor "super" amps appeared, which were direct coupled to the load. These were in the 150 to 200 watt per channel range. The output devices were not reliable and most had no speaker protection from DC offset when the power transistors blew which was frequent.
The Accuphase P-300 was one of the few that did and had relay speaker protection. However relay protection is relatively slow and these amps can still destroy speakers.
Power is 200 watts into 4 ohms and 150 watts into 8 ohms.
Last year of production I think was 1973.
I really do not recommend using these early transistor "super" amps, for reasons of reliability and the presence of significant crossover distortion.
Most of us used tubes well into the seventies. I switched from a DIY Williamson design in 1972 with the Quad 303. It's still going and I have never opened the case.