PS Audio Amp

Hi everyone, PS Audio for some reason didn't used to include important information like the amp's impedance in the owner's manual. I haven't found anything online so I was wondering if anyone happens to know the impedance of the PS Audio Two C Plus that was made in the mid 80's

If anyone has an Audio magazine Annual Equipment Directory from 1983-88ish it would probably be in there. Any help would be appreciated.
I owned this amp for over 20 years before it finally died. I have the detailed spec sheet for the amp, but it never mentioned input impedance. However, for some reason that I can no longer remember, I wrote down the input impedance on the spec sheet. It was 47K ohms.