With ground loops I have managed to destroy 2 dip props, 2 QS boards, probably a proto board, various component parts and a propplug! I thought I had the ground loop problem solved, but NO I continue to destroy things! Bless Erco as years ago he turned me onto a $4.99 boost convertor that outputs up to 24 volts or more. I connected the converter to a large USB battery pack and set the output to the required voltage to run my various boards that want +7.5 V to 9V. That should eliminate any ground loops. I just wish I had remembered that I had it sooner. It powers the boards just fine. Now all I have to do is replace the propplug and a few prop chips. The hardest loss will be the protoboard as I don't have the facility to replace the prop on it. I won't know if the protoboard is gone until I get the new propplug and rev D obsoletes all of my Mini-USB cords. Oh well such is life!