I had my 1200w (4x300w) amp connected using 10gauge wire, which worked, but when i turn the built in screen on (flash lights) the amp power light fades slowly then goes off & no bass. But the screen stays on.
This happens with speakers connected & disconnected.
Took the amp to halfords & they tested it & it worked fine.
I then by a 4gauge kit as i though it may be drawing too much current etc & wire that up, but still the same problem.
I have cleaned th positive terminal on the battery & drilled, saned & screwed the earth in the boot flooring.
I have also tried it on the seatbelt bolt as suggested.
Where is the best earth to use?
Any one have any ideas?