I have hiss in the new system.

Hiss is most likely due to a mismatch in the gain settings. Try turning the gains on the amplifier so that the volume goes down. Then turn up the head unit volume. After making this adjustment, if you need more volume, use one of our dedicated line drivers, either the Overdrive or the Matrix. This will maximize your signal gain while keeping the hiss out of the signal. To see how this is done, take a couple of minutes and watch the Level Matching video.