Amp grounds

hi,

Anyone help. I have two amplifiers and i have some ground noise. Question is can i use two seperate ground points either side of the car as the current ground is not good enough, so i need to move it.

The mixed reviews say to use the same ground, but where there positioned i wont be able two unless one ground wire is longer than 18 inches

Many thanks,
 
Its not totally off putting, but its there. I got a ground loop isolator today that didnt improve it so its suggested for me to use a new earth point. Tbh, currently its earthed to metal thats joined to the main chassis. The noise is a slight buzzing, not whining or anything.

Yer, there intact..