JVC dual bridgeble AMP

Have the speaker checked out and if it checks good you need to take the amp back to the repair center and have them test it better. Most repair centers have a 30 day warranty on the work they perform. Make sure they know what the problem is in detail, so they know how to check it properly. But my first thought is the speaker could be faulty. You can check the speaker yourself by switching them at the amplifier. If the same speaker sounds bad you know it is the speaker that is bad. If the sound is bad from the other speaker, then the amp is bad unless it is coming from the head unit. You can also switch the RCA input jacks after that and see if the problem changes speakers, if so, the RCA output of the head unit is bad, but that is less likely.