MA2275 Issue need some advice

It would seem odd for two tubes to have a bad side. Those two phono tubes are like a spare pair of used tubes, when using them in the other inputs like CD. It still might be worth trying a couple of new 12AX7s. All the other tubes should change the distortion over to the other channel when you switched them, one would think. Did you swap the CD left and right outputs to the amp to make sure the CD player left channel doesn't have the distortion? Or, use another source, like a spare CD player, DVD player, etc. If you did and no changes, I'm thinking repair time. Don't hold me to this though. Anything is possible...

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.