Amp "pop" - need help

just purchased a McCormack DNA-1 Deluxe. While the sound quality is greatly improved - better stereo separation, deeper bass, less harsh highs, improved dynamics - I have noticed the amp gets quite hot. After just a few hours the heat sinks are hot enough to be quite uncomfortable to the touch. Worse, though, the amp makes a popping noise as it heats up. Sounds a bit like metal expansion. . .the wife says it sounds like the last kernel of corn popping in the microwave.
Not sure if this is an issue but it sure is a big change over the previous amp that would run all day without overheating.

Any ideas?
I've owned several DNA-2's. My current amp is a DNA-2 Revision A version and I notice this once or twice 'popping' sound typically after I have turned off the amp (during cool down). I think it has to do with the heat sinks expanding and shrinking as you suggest.

But if you are still concerned, you might contact Steve McCormack at

DNA-1 is biased higher into Class A, if I remember correctly. Mine ran substantially hotter than my 0.5.
My Krell amp does the same. It is the heat sinks expanding. Once it heats up it stops but after turning it off, it does it as it cools down. Krell adds some sort of damping to their newer amps. It won't hurt anything if it doesn't bother you.
Thank you all. I am reassured. now, back to my previously scheduled listening. . . . .
Leave amp on at all times and this won't be a problem. I leave my Threshold on 24/7 (150 wpc of pure Class A). It sounds better and is easier on the internal components, no power rushes. I leave all SS equipment on at all times. YMMV.

I have a Classe CA400 that would make a loud metallic snap/pop/click. I removed the top plate and refastened it. The noise went away. I figured that maybe the cover was expanding. I was right.
I absolutely agree with all above. Just metal expansion and contraction and not a problem per se. Leaving the amp on is a benefit sonically as well. As for the heat isuue...take heart,Krells heat sinks run about 145 F in class A and my Plinius SA 100 Mkll runs a blistering 160F !! in Class A.. Now thats uncomforatble!

Are we REALLY to leave the amp on 24/7?

Gosh, I should move back to the east coast and use the amp to heat the room. I can't imagine that kind of heat build-up is good for the components baking in the case.
Well..I agreed with those above..but truth be told,personally I dont leave it on 24/7. I could in Class AB and just switch to Class A when ready to listen. The Plinius amps have that provision..But many amps dont, and the heat can be excessive. As a former East Coaster myself, I really liked my old KSA 100 heating the back end of the house! The better solution may be a soft turn on power line conditioner such as those from Virtual Mode. Using single component Passive filtering and surge protection without chokes or MOV's. It does very well for SS amps and protects against the in-rush of current upon turn on. I do leave all my other SS components on 24/7.. (CD and tuner.)