Static Noises after install of android head unit with built in dsp

Hello everyone. I recently upgraded my head unit from a pioneer AVH G255BT to an android Head unit (ONE NAV ref:ON019-A101M) with built in DSP. I run a single amp Pioneer Gm-D9604 powering my speaker (ref: Kicker Cs series with coaxial rear and component front ) and a pioneer subwoofer (ref: TS-W311D4 ) running is bridge mode.

I noticed weird noises coming from my speaker and sub. I've check all the grounds with a multimeter and all of them gave a resistance of around 0.04 ohm(just for the head unit) . I've guess that the ground works fine. When the invertor does its things I can hear the whining on the speaker and some goes for the clicks noise of my hazards lights/blinkers .
I also unplugged the RCAs and turned the amp and head unit on and there was no more noise. I assume its from the head unit itself.
As for the gain it wasn't altered , it was left how it was when i had my pioneer head unit.
I've looked online for solutions but till now I've got no concrete conclusion, some say ground the rca but other says that grounding RCA outputs is harmful to the system.

This head unit doesn't have the RCA directly onto the back of the system, it uses a white connector with wires which goes to a box which has some sort of pcb and (has its own power and ground wires) which then provide output to RCA to speaker and the subwoofer rca is a single rca cable off the connector .

Before I go out and but those so called Isolators which might not solve the issue , any of you professional here has an idea of what could be the issue or any fix.

 

I've reworked all the possible grounds as you said i made the "box with pcb" use the same ground as the head unit. I've even bolted the other ground wires(parking brake) to the chassis part just a bit further back of the center air vents.
I've attached a few pictures of the intermediate pcb box and how the cables are plugged at the back hope this will give you an idea how it is.

next thing I'll try is to take the ground of my amp and bolt it to where the 12v battery grounds are bolted and see if this fixes the issue.

I've read somewhere that some manufactures have these issue/flaws from factory but it remain "hidden" to the oem head unit until the audio system gets upgraded.