I am running two amps one for the house speakers and the other for the sub and tower speakers. The tower amp is a Alpine PDX5. Right now the ZXM is only running to the house amp and the tower channel of the PDX. The sub bypasses the ZXM going straight from the head unit SW outputs to the PDX sub channel.

Can I use a Y splitter and run the sub through the ZXM as well as the tower channel and then have pre-amp volume control of the sub tied into the tower? Would the SW control on the head unit still work properly? Or should I just scoop up another ZXM and run the sub through it so I have three zone control?