so my friend just got this jl 4 channel amp to power his inf. kappa interiors and when he hooked it up, he gets a whining noise coming through all of the interiors and when he hits the gas, the noise gets louder! i talked to a few ppl but keep getting diff answers as to what it can be. someone said to get something (forgot what he called it) to plug your rca's into. he said its a small cube or something. another person told me its a bad ground! his amp with his sub is fine. no whining coming out of the sub. he also has a capacitor hooked up....dont know who did the install! would it be two seperate grounds for the sub and interiors? doesn't the ground and power come off of the capacitor? im really lost and could use some insight please! reps given and thanx in advance!