Hum W/ Stock HU & Speakers

Hi, i have a 2013 TRD Sport with the touchscreen non-nav that had an annoying feedback noise that i eventually tracked to the head unit. I am receiving a hum from the speakers even when the radio is off. Reading through some of the search results, I attempted to reground with no change. Everything is completely stock, stock amp stock sub stock speakers.

Any help is appreciated, it's driving me crazy!

 

Very weird even with the HU turned off to hear the hum. Does the hum change with volume (no music but HU on?) or is it constant?

 

It's constant. Doesn't change pitch whether the truck is off or on, or whether the radio is off or on.

 

What about if you turn your volume up or down does the pitch change?

 

It's completely constant both in pitch and volume with every possible combination of ignition setting, power setting on the hu, and volume. There is no peace unless windows down or music over level 20

 

My guess since everything is stock is something to do with the power line going into the HU either being too close/touching a speaker out line. Since its constant and doesn't change pitch I would think it just has to be something with the power in line.

 

i'll try and isolate the power wire and insulate it a bit more. thanks for the suggestion

 

resurrecting this... hoping for some help. isolated the power wire, re-grounded, bought another head unit. still an extremely annoying whine coming from the speakers..