I just bought a hardwired personal monitor. Will I have to have the mixer to use this, or will it hook directly to my snake or pa system.
The input signal to your PSM400 hardwired system must be at line level. A line level signal is available from any mixer's main output, a headphone output, or an aux output.
You cannot drive your PSM400 hardwired system directly from a microphone signal. A mic level signal is only 1/1000 the strength of a line level signal.