My little Dillemma...

[luvinthebass 5,000+ posts]

definitley a thump

maybe your gain is to high or your amp doesn't have that anti-thump thing for it

 

[ex_03]

If its a ground loop you may want to upgrade : Power,Ground cables under the hood. From battery to body and alternator to battery and battery to amp. The problem is to many things grounded to the car and a stock ground at the battery, So the isolater is more like a band-aid.