Q: Have torn apart car to diagnose speaker problems. Speakers cut out only while driving. Both + and - for speaker wires have 6v

Have inspected all speaker wires for shorts, nothing. Have unplugged each speaker one by one to isolate, nothing changes. Found that backprobing directly out of Dual xnav27bt (aftermarket unit) harness to speaker wires, 6v power is present on both power and ground. Source v at key turn on and without key on correct wires( 12v and constant) ...have a power antenna. Cut that wire and used bt to see if issue changed, did not. Must be a short in unit but this is the second brand new one i have put in and it makes no difference, issue doesnt change
My car has an automatic transmission.