Rule of thumb. Always ground the amp to the battery and be done with it.

 

NEVER ground the same connection to two different spots, two different ground potentials boss.

 

 

Which candy amp do you have?

 

Some cheap micro amps use MULTIPLE smaller circuits to save space. You can't get the full strength out of the amp running a single line. I don't know those amps but if they use a wire harness that's 16 gauge or smaller that should tell you something.

Look at the "Dual" brand Walmart special amps. They have 3 grounds!

 

Check this out. Look at tiny the traces for the three grounds. No wonder they want three grounds hooked up. How they avoid a ground loop is beyond me.