I have a 4ch amp using 2 channels to run a split system. I have a monoblock amp that runs a sub. At high volume the sub stops playing. The monoblock stays on and the 4ch protect led starts to flicker. The weird part is that the splits keep playing. Now if I disconnect the 4ch amp the sub plays through all volumes. As soon as I plug the 4ch back in the sub turns off. Is it possible that the 4ch is faulty and causes the sub to stop playing even though it runs from a completely different amp?