Braminator - I had a BPA then HPA-2.. I think I got the HPA the last year they were made. I had no issues with mine - none. I tried it with a Dehavilland Ultra Verve preamp and the combo was just great. The HPA was much better sounding then the smaller Proceed.
If, as you say the amp is 'mint', you just got a an excellent buy for $500.. (IMO) good luck
If, as you say the amp is 'mint', you just got a an excellent buy for $500.. (IMO) good luck