If you do want to keep your amp, this device might come in handy:
SM Pro Nano Patch
It's a small passive volume control for analog signals.
It isn't that expensive but not cheap either, since it will cost you about the same as that Harman Kardon amp you have dug out.
SM Pro Nano Patch
It's a small passive volume control for analog signals.
It isn't that expensive but not cheap either, since it will cost you about the same as that Harman Kardon amp you have dug out.

















Tantalum and Riken resistors, Russian MIL PIO and Elna caps, MIL spec power transformers, but the best part was a MIL spec step volume control. It was laser cut on the diamond composite board. These things cost about 90 rubles each for bulk shipments of 5000 when the factories were buying them from one another in 1970's. My friend got them 10 for $1 