Greetings! Ok, your amp has an XLR (3-prong) Low-Impedance input on Channel 1 for a Mic. All the other inputs are 1/4" High Impedance inputs, which are for instruments and/or other High Impedance items including low quality High Impedance Microphones. The SM48S is a high quality Low Impedance microphone, so if you use it with a 1/4" plug, it will be in a High Impedance channel, and will be very LOW in volume in comparison with everything else. So, you must use an XLR (3 prong) cable from the Mic to the Channel 1 input on your amp. That will do the trick. Good Luck with your new amp and Mic!