I use this set recently, he succeeded to a set M504-P304 gave me any satisfaction for many years. Construction even more massive and square of this set, making it the heart of a set of audio quality. XLR connectors on the spot in a class of high-end hardware. No tone control or balance, but an adjustable gain, apart from the overall volume for each channel.
It is a set double mono, with a real symmetric separation. Actually two amps in one box. Its weight of 31kg in said enough to respect the reserve of available power, which is around 300 watts per channel.
The definition, the seat depth of restitution encourages listening over a long period without ear fatigue.
The convenience is that volume has a motor and the same goes for the selector input.
Considering the price to acquire it in time, I do not really voice what I could get on the market, if not a little low-end stereo amp with no body.