alternator whine/grounding head unit?

[fredberg]

my system consists of an Alpine HU and 1 MTX amp powering all 4 speakers (6X9's). i used to have bad alternator whine becuz the RCA and speaker wires ran alongside the power wire for the amp. when i moved the RCA n speaker wires away from the power wire, the whine diminished dramatically.

but there is a little whine left, which i wanna try to get rid of. im guessing, the only way to solve that is properly grounding the HU. my amp is grounded to the chassis near the trunk. i made sure to sand off the paint for the best contact.

my HU is grounded to factory ground. i've read differing opinions on where to ground it. shuld i ground it to the same point of the amp? or shuld i just pick a better place, say the firewall, and make a good ground contact there?

lemme know b4 i have to start removing panels n stuff