Electro Harmonix voice Box Harmony Machine when power supply connected i heard hum from the mic output. With or without power and try to trace the path signal, I found out the +positive signal bleeds to negative - #1 pin on XLR mic output. How can I block the the power from entering to the negative pin on XLR mic output.

SOURCE: Can I hook up 2 separate power amps to PMP3000? I

Better way... Connect the main speakers via the Speakons and then put a Power Subwoofer to one of the Monitor connections IF you are not using both stage monitors. If you need to kill the lows to the mains, use the EQ in the PMP-3000.

Use the EQ that is USUALLY on the subwoofer to kill the highs to the sub.

Lot less cables and hardware.

REMEMBER for equipment safety, power ALL interconnected equipment from the same source be it a receptacle or power distribution system.

Powering parts of a system from receptacles strewn around a room is asking for trouble of ground loops and ground faults.

SOURCE: the mixer has xlr main output x2 and jack

The output jacks are PSUEDO balanced so use TRS cables and you should be able to drive two amps from each with no problem either as a WYE or daisy chained connection. The PSUEDO balanced connections do NOT drive differential voltages, but tie the return to ground through a 120 ohm resistor. It is imperative that you power ALL the amps and the mixer from the SAME receptacle or power conditioner. If you don't do this, expect lots of hum and risk of ground bounce damage to your equipment. Run extension cord if you need to.