Humm noise - rockford r2-300x4 amp

[Sito]

Hi,

Had a specialist install this amp in my car(electric Car - ioniq 5).
The setup is high level 4 Channel amp.
After the installation, i hear hummiing sound from speakers even when the audio system is turned off, it only disappears when I lower the gain to minimum in amp.
I tried disconnecting the amp input that comes from HUD but the noise still remains.
I also checked the ground connection to chasis(checked no coating on screw as well) still didnt help.
Can any one give me idea how can I proceed from here?

Thanks

 

[1aespinoza]

I tried disconnecting the amp input that comes from HUD but the noise still remains.

Does this mean you disconnected the RCAs that are on the amp? If yes, then the amp is the issue. What make and model is it? Is it connected with an Line Output Converter or RCAs from the back of the radio?