Question Bluetooth amplifier ground issue...

[Cradiak]

I am using an old Bluetooth speaker for my audio amplifier for My GCP, but I ran into an issue. The amplifier's speaker doesn't have a common ground, so it won't work when I connect it to the gamecube. If I power the amplifier externally, then the sound works fine, but if the amp is powered from the GC, I get power but no sound. Is there a way to remedy this?

The ground I'm using is the pin next to 5v and the video out pin.

 

[Stitches]

Photos of all wiring pls