For quite a while I happily used a PM351 to run my IEM set up. I had an issue, sent it to a tech to get it fixed. A capacitor crapped itself or something. When I got it back, I started to notice a phase cancellation issue with my vocals. I was taking a FOH mix into the line input, and running my vocals thru the mic in and out. My understanding is that if I am adding my vocal to a mix that has my vocal in it already, without flipping the phase on it, they will cancel each other out. I'm wondering if during the repair, something has been changed. Does the thru on the PM351 have the phase flipped so this can't happen? Does someone have one that can check this and report back so I can compare results? Has anyone else experienced this issue? I'm currently using a Yamaha MG-06 mixer to run my IEM, with a splitter box for my vocals. If I don't hit the phase 180° switch on the splitter so that the isolated out from the box is flipped, I get cancellation. Any help is appreciated!