Sounds like a cold soldier connection in your amp. I had the same problem with a Classe CAP151 years ago. I sent it back to Canada 3 times to fix the 3 cold solder joints. I would receive it back and months later another problem showed up. If you find a good tech, I would have him go over all the connections.
On a side note, I once drove 500 miles each way, (Alone) all in one day and night to drive to Annapolis, MD from RI to pick up a pair of speakers the owner wouldn’t ship. Left at 5AM and got back home at 11:30 PM. Never ever again! I had a pounding headache for 3 days after.
On a side note, I once drove 500 miles each way, (Alone) all in one day and night to drive to Annapolis, MD from RI to pick up a pair of speakers the owner wouldn’t ship. Left at 5AM and got back home at 11:30 PM. Never ever again! I had a pounding headache for 3 days after.