-Bad ground at head unit-Bad ground at amplifier
Ive thought of this, as my deck is grounded to the harness, but when it is grounded to the frame, the whine is louder and it makes a pop when it turns on.
-Multiple amps grounded to different locations
Both amps are grounded at the battery with a block
-Bad head unit e.g. Pioneer with blown pico fuse
not possible, brand new deck, JVC.
-Bad ground somewhere in the big 3
probably the cause, ive thought of re grounding my alternator to see if it could solve it.
-Bad alternator (this was my problem - my DC Power alt took my whine completely away even without new wiring)
it's a possiblity, my car is only 6 years old though and im the only owner so probably not but you never know...
-Noisy component in car e.g. fuel pump
also a maybe, with the car off and the deck on, if i turn the key to on, i can here the fuel pump cycle.
-Bad connection somewhere, either in the cable or the connectors
rewired everything this winter, triple checked.
Check your grounds. Try running a portable CD/MP3 player directly into the amp. If that doesn't show the problem then try a ground loop isolator on the RCAs. Amazon has one for like $6, Prime eligible.
This seems like my only option, if the alternator it self is not the cause.