Hi, I just modded my SX P clone by adding a Dimarzio Model One (DP120). I gave each pup its own stacked vol/tone, and wired the output from each vol pot to its own stud on a stereo jack (common ground). Using full stereo cabling everything works fine. That is, TRS instrument cable to a stereo Y splitter. I swap first one plug into my amp and I get the Model One. Then I swap the other output from the y to the amp and I get the P. Sweet. I take the Y out of the signal and use a Stereo to mono adapter (Hosa model GPP290 " Sums stereo left and right to mono") and things get a little funky. I have to have both vols up to get a signal. I'd like to have control over which pup is on and how much. If I turn down one vol, it seems to turn down both. Hmmmm. Any ideas? Something obvious that I'm missing?