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?
audio_newb
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.

Regards,
John
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.