I bought two 100K input potentiometers from ebay and installed them, put the amp together and it looks pretty good.
The bad, it sounds like crap, there is not enough gain in both channels (the needles barley come off of the bottom when the receiver is all the way up) and it is not as loud as a 350 watt amp should be, not as loud as the PL400. Also the right channel is distorted.
I am using a Pioneer SX950 pre-amp out jacks and (4 ohm impedance) Ohm I speakers. This setup sound fine using my PL400 amp.
I will bring the amp back to the bench, but not really sure what to check.