I would like to connect my usb mixer (for music recordng) to NAD c320. The connection apparently requires 1/4'to RCA cable (which I have), however when I connect the mixer output to AUX input on the amplifier, there is no sound. I also tried to connect the mixer output to Line input as well as CD or disk inputs on the amplifier, but it still does not work. I wonder if the problem may be that my CD player (also NAD) is simultaneously connected to CD inputs on the amplifier. Thanks!

Audio Players & Recorders - NAD - C320 2-Channel Amplifier