Do you want to expand your amplifier so that you can use more microphones as you do not have such provision in your amplifier.

Professional Microphone Mini Mixer 8 Channel Portable Combines Eight microphone audio signals into one for applications like karaoke. No change in sound quality.

Each input has its own volume control. It can be used with a 9 volt battery since the power usage is hardly anything so the battery will last for months.Also if you wish you can use a external 9V power supply.The battery or power supply should be of good quality.

8 mic inputs male jack plugs Channel A and Channel B both will have a master control for each 4 channels . Low impedance

Ref:WF-MM8L