McIntosh power issue

Hello,

Just recently, I’ve noticed when I power on my MC7300 and MC7150, there is the pop, the meters jump and then they hang around -50 to -48db on either amp instead of going back to their resting positions when no signal is being sent to them. Both are in the same room, same circuitry. There is no input being provided to these amps when they do this . I’ve also noticed that the meters do not begin to move while I’m sending signal to them from a C50 pre until the C50 is turned up some, around 27-30. 

I’ve been searching for days on what might be causing this issue and all I get is marketing literature from Mc and explanations on how to interpret these meters. 

The amps are also slightly humming, they may have before and I just didn’t notice but something is not normal. Really hoping it’s my power and not the amps. 

 Can some one please tell me what this means or help give me some ideas to search on? 

Thank you very much,

Chris C