Hey I think you need a DI.
Run the Sonic Port into the DI. Take the throught from the DI and send that into the input of the amp. Take the XLR from the Di and send that to the PA.
I was trying to do something simliar today. Running a 1/4 to XLR lead straight to the PA but the signal was so low. I needed to run a DI. I used a passive DI and that helped but the signal still seemed low. Have a look at an active DI. I am looking it as well.
I hope I helped.
Cheers Tim