So I finally decided to ground my RCAs before as the hissing noise got a lot louder since I first installed my system. Also, right speaker had crackling noise coming out of it sometimes as well as the hissing noise. Well, today I grounded my RCAs and hissing noise is completely gone, but my right speaker sounds muddy (theres some static/hissing coming from it.. not the alternator noise I had before)... not as alive as the left one... what could be wrong?

 

So someone on caraudio just said it's bad/pinched/torn RCA cable

 

or the pin may be loose on the headunit harness.

finally figured out thats what was wrong with my f90-bt

 

I heard a pretty good snap when i pushed the harness in.. can't be that... i think... and how did u find out it was that lol?