A very nice, simple, excellent sounding amplifier. These were part of a Midi system, the only light is the power indicator light on the front panel. These amplifiers were well thought out and designed to be compact but with design feature ahead of the pack, Toroidal power transformer, custom made cast alloy heat sinks and a very good phono amplifier. This example was needing a little tlc, it was very dirty inside, I cleaned it out, cleaned and lubed the switches and controls. It was faulty on the left channel; when you turned up the volume the sound became badly distorted. After performing some tests, and a few measurements I tracked it down to an open emitter resistor on the power out put transistor. Emitter resistors often blow when the output is blown (one or both output transistors shorted and often the drivers as well) but they don't often go on their own and the fact the channel still produced output did not make diagnosis easy, still if you follow a procedure and do a series of logical tests you can usually track down the weird faults in good time. Well worth the effort fixing it.