I had a request for a circuit diagram, so I will upload it.
The main body model is written as SM-11B, but it is written as MS-11B in the circuit diagram. The latter is considered correct.
In retrospect, this amp didn't get very high output. Since it is a 6BQ5 single, I think it is about 4W, but I remember that only about 2W was output. Since the 12AX7 Phono EQ amplifier drives the heater at 5.5V, the emission drops at an early stage, so if you give the rated 6.3V with a tube checker and form it, the emission (gm) may be restored. Lowering the heater voltage will reduce noise.
