Amp showing its age?

Aging electrolytic capacitors. Have you had any replaced in the time of your ownership?

What he said. Some open circuit (parallel) output transistors could also do this.

@chenry, @noromance  Never had it checked out, nothing replaced, but warranty had expired before I noticed the slippage in performance, and the thing weighs a ton and is long discontinued. Of course you must be right. Guess I will sell it with a note to check capacitors and/or use with 8ohm speakers until it dies. Thanks! 

If you kept it as long as you did, it can’t have been bad. It might be worthwhile having the unit serviced and bad caps replaced along with anything else needing replacing, As a second system amplifier it might be a familiar and welcome value, it seems as if it was very well made to have lasted so long.

@chenry  Makes total sense and no doubt you are right. Thanks, I will look into that.