I've got another one of those gigs comming up where I have to do the PA as well as play bass. However it's looking more and more like I'm going to have very little time to set up, tune the foldback, then soundcheck. I've found I spend more time tuning the foldback than anything and had an idea which may speed things up. Trouble is I don't really know if it will work. I have a multimeter that can measure frequency in Hz. I was thinking that I could run a lead from the parallel output of the wedge to the multimeter. Turn the monitor volume up until I get a little bit of feedback, and hopefully the multimeter will tell me what frequency is feeding - or will it?