MA2275 Issue need some advice

Are you positive it is the Mac? Have you swapped ICs left to right at the source only? Or try another set of interconnects from source to amp. You may be looking at the wrong component for trouble. Good luck.

There are fuses on the power tube board sections of both left and right channels if one of these fuses blows you may get noise like you describe and also low volume output from the channel with the blown fuse. It then may be that a new fuse will correct the problem or there may be a bad resistor or other part on the circuit board. Don't know if this is the problem with your amp but is another possibility.

JLind...Done everything and every combination including moving the Mac to my other system...doing the same thing, its the left channel of the Mac so heading to the Doctor in the morning for 3 weeks of therapy. What really irritates me is I just bought it from someone on AudiogoN as a 9/10 in perfect mint condition. It was doing this the moment I hooked it up and he is pleading the fifth.

Kbell...thanks for the input about the fuses on the power tube board, the channel with the distortion problem is actually louder than the channel that works well.

G5flier, I would recommend using the augiogon system including feedback and dispute process to get it right with you and the seller. Based on what you have said, the repair should be the responsibility of the seller or you should be able to return it for a full refund. I can see a tube getting damaged during shipping but it doesn't seem like this is your issue.