I just purchased, supposedly, a Dynaco PAS-3 pre-amp and an ST70 power
amp which were supposed to be in "mint" condition. However, the
pre-amp turned out to be a PAT-5 solid-state model rather than the
PAS-3 toob pre-amp. And the ST70 has weak distorted output in both
channels.

Question No. 1: Is the PAT-5 pre-amp anywhere near as desirable as the
PAS-3? Should I return the PAT-5 and demand a refund?

Question No. 2: If you were me, where would you start troubleshooting
the ST70?