Can I plug my musical instrument into the mixer?

Yes, guitars and basses had better have di boxes, or the effectors had better have box shapes. The keyboard connects the left and right channels. You can use the left and right channels or one channel. It is troublesome to pick up the drum set. The microphone interface on the mixer is either fully connected to the condenser microphone or fully connected to the moving coil. If the capacitor is connected, the mixer needs to be connected to the 48V phantom power supply, and the moving coil cannot be connected, which may burn out!