What were the best years for McIntosh power amps...

In terms of sound quality, reliability, and holding it’s value McIntosh bested them all.

Your opinion, to me the sound quality went south, when they introduced output transformers for ss amp, which as you say made them, "at least" bomb proof.

One of the best Mac's ever made.
https://upload.wikimedia.org/wikipedia/commons/9/91/Mcintosh-MC275-glow.jpg

Cheers George

What were the best years for McIntosh power amps

The original 275 were their best years.
Then ss with output transformers??????????????????

Cheers George