Recently on my 2010 LS, the rear sub will randomly hum very loudly and then play music like normal. It does it randomly and on and off. Is this an amp problem? I have the ML system. Thanks in advance.

 

When I've read of amp problems on this forum they usually just completely go (a loud hum that doesn't stop). Your intermittent problem almost sounds like a loose connection somewhere.

 

Sounds like the amp may be in the process of going out, leaking an oscillating low frequency to the sub. Call United Radio in Syracuse NY to see if they are familiar with this issue. They certainly have repaired a lot of '07 - '12 ML amps.