Source of Static?

I'm experiencing intemittent static through both speakers. Not only that, but the volume momentarily drops while static is heard. It sounds like an incomplete connection. 

I skimmmed through past threads and one possibility, it seems, is a bad solder joint in my integrated. 

Unfortunately, I don't have another amp to swap into the system.

Any suggestions for other things to try, before I send amp back to manufacterer?