I assumed you meant you had an integrated amplifier in your main system since you had previously referred to the Yamaha as simply "amp". So, you have a preamp (no phono section) and separate amplifier in your main system. Correct? Can I also assume that the Yamaha "amp" you refer to is an integrated amplifier (preamp/amp in one chassis)? When connecting the Yamaha to the preamp in your main system make sure that the source selector is set to "Phono". Then connect the Yamaha to one of the preamp's inputs as you would any component. Should work. Also, MAKE SURE YOU TURN OFF THE COMPONENTS BEFORE PLUGGING/UNPLUGGING CABLES.