I have Yamaha RXV 2400 receiver and I hook up my laser disk player.Well I know if I use DTS I don't need a demodulator,but if I use AC-3 DD that you are to use a demodulator.I thought if you have Pro logic that Pro logic IIx is to use it to seperate sounds to all of my speakers.Another word,do I need to buy AC-3 demodulator.THX