what brand gold plated rca u're using? usually not the connector to be culprit for the noise, but the cable itself, the shielding, quality.
what DIY cable u're using also?
i have one ah beng way of solution la as i am doing that for my current rca cable also.
take a red and black cable then put each wire to respective rca and plug in ur HU. the other end of red/black cable u joint together the wire and u ground it the HU body.
try it out and see what the out come la.
maybe u can change ur grounding point of your amp also as i read from one page that the seat belt bolt there not a very good grounding point for amp also.
At the beginning my turbo was creeping till 0.8 ..
Now want to boost 1bar
Fixed metal gasket
Fixed in the Fish Tank Valve
My max boost is 0.9 .. i open how many valves also my boost will stick to 0.9
wht could be...