[mikegett]

When I mentioned a temporary ground line to the battery, I didn't mean for the amp. Most likely, your noise is coming from the loc. If the new one has the same problem then run its ground straight to the battery. A simple 14-12 guage wire will be fine. It only pulls a few amps. I always keep a spare 17 foot wire just for this purpose. Ground loops can come from multiple equipment so the easiest way to find out what one is grounding it to the battery. If it goes away then you need to relocate your ground to a different location or place a ground loop isolater. In the case of a LOC with built in ground, you don't have a option to relocate.