I was looking at the schematics today and noticed that the earliest PCR800s (the ones with the sided power switch, vented front cover and blinking power light) have a board which only acomodates 4 mosfets per channel, I remember when I vacuumed one of these. These boards should be numbered 1699. I don't have any of these amps but I'll be buying some in the future. My friend in florida has a pair of these bridged through a PRO CONTROL THREE preamplifier, he has a huge sound room and they rock the walls and at the same time provide a very clean sound. The newer boards with space for 6 mosfets per channel are numbered 1806.
Cheers.