Component speakers hissing

I've upgraded my system with a pioneerNEX4660, and a pioneer 5 channel amp. I'm running the 3 OE speakers in the dash off the HU like the factory does and I've got 3 sets of RCA for F/R/SW running to the new amp. I'm picking up all my speaker wires at the factory amp location under the seat with a bypass harness. I replaced the front woofers with 3 ohm JBL components (added tweeters in the sail panels)

Everything sounds good, however im getting a slight hiss out of the components (all 4). Even with gain all the way down and no music playing. The hiss starts as soon as the HU has finish booting. I've unplugged the RCAs to rule out some interference and the hiss remains.

The OE rears do not do this. Any thoughts?

 

My guess would be the ground. Make sure it is making good contact. If it is, maybe replace with a thicker gage wire.

 

Where did you mount the ground cable?
Did you sand the paint off the chassis first?
Are your rcas side by side the amp power cable?

 

Confusing but Im trying to make sense of it.

So you ran RCAs from the HU to amp for the speakers you installed. You unplug the RCAs but the hiss remains?

If I understand that correctly you removed the signal cable to the speakers and still had hiss, if you did all 4 and still had hiss then its not the amp nor the speakers, since theyre effectively out of the system at that point.

I'm also confused about your "picking up the speaker wires at the stock amp." If you mean that you are running speaker out from the amp to the stock wires under the seat then make sure you're not tapping in pre OE amp.