Although I was actually a little surprised to begin with that the voltage you reported would cause any problems, the fact that each of two monoblocks is acting up at the same time would tend to eliminate something like a parts failure - unless they both got zapped by a large power-line event that you didn't know about. Other possibility is that the tubes are growing too old together all around.
Conversely, are you absolutely sure that the problems originate in your amps at all? In a tube preamp, a single tube will often handle both channels. If you've got a tube pre and haven't ruled this out already, the symptoms could be worse in one channel than the other if a tube is going bad. If you need to, try running the amps with the preamp off, or better yet, with the amp inputs disconnected to rule out possible jack- or cable-related culprits. (Can you still cancel the order on that voltage regulator?) Gook luck!
Conversely, are you absolutely sure that the problems originate in your amps at all? In a tube preamp, a single tube will often handle both channels. If you've got a tube pre and haven't ruled this out already, the symptoms could be worse in one channel than the other if a tube is going bad. If you need to, try running the amps with the preamp off, or better yet, with the amp inputs disconnected to rule out possible jack- or cable-related culprits. (Can you still cancel the order on that voltage regulator?) Gook luck!