eliminate 24v - ground loop that is destroying components
Your problem is that you connected the batteries in series and let them share the \$V+\$ while at the same time GND is shared. That can't work.

The GND of the left circuit is the positive terminal of the left battery.
The GND of the right circuit is the negative terminal of the left battery.

Both GNDs are connected via Out- and Audio-.

I.e. the left battery is shorted via V-(right) --- Audio- --- Out- --- V+(left):



The simplest way to eliminate the problem is to supply the left circuit only by the left battery. I.e. both \$V-\$ go to the negative terminal of the left battery: