tube amp noise

I would also double check the fuse to see if there is some slight coloration on the glass.

How many tubes do you have to replace?

Same thing happened to me. New preamp unit and some hissing with popping noise once in a while. Even after tube rolling.

Happened to be an interconnect problem. The connectors themselves got a little loose. Tightened them and the problem was solved.

Another possibility that was brought to me by a technician is older cabling. An old interconnect that has remained plugged and untouched for many years can break inside its shielding sleeve without any apparent marks once it is moved or twisted again. Witnessed that problem at my friend's place when he changed is amplifier.

Hook up to a expendable pair of speakers and gently wiggle each tube and you will likely find a bad socket. The tube which swims the most is likely the bad site. Also, look for leaky capacitors, brown goo, oozing from the end. Jallen

Thanks for all the advices. This amp weighs 110 lbs with box so want to go over all possibilities before I take it in. For now, I think I can live with it given I have 2 more years of warranty and can take it in if it gets worse.

I don't think it's interconnect since it happens in all channels and don't think it's tubes since 2 sets (1 old 1 new) have same issues. Might be a bad socket or capacitor or fuse. Is McIntosh MA2275 easy to open up to check for capacitor or fuse? Thanks.

Ron from McIntosh recommended I remove my power conditioner and plug it straight to the wall outlet and surprisingly this seemed to have mitigated the problem noticeably. Not sure if it's the power conditioner or other components I had plugged to it, but now I just have the amp plugged in wihthout any power conditioner and the popping is less frequent and much quieter when it does happen. Pretty depressing knowing I could've saved $500 and lot of headache by not getting one.