I played a gig at the weekend and my set up was as above. Line6 Realy G30, in to my BDDI. XLR goes to small PA, jack out (with effected signal) goes to my MarkBass F1 head. With the BDDI connected to the PA there was a whistling sound coming from my cab. Switching ground lift on helped but it didnt get rid of it completely. when i disconnected the XLR it went. It wasnt a really loud whistle, just one of those annoying sounds you can here between the band playing. Ive only done two gigs with the Line 6, and each has been problematic although ive managed to over come the issues more or less. Ive had no issues with the system working, just a few new "noises" in the background. So, im wondering could this just be bad earthing at this one venue? We wont be going back as it was a one off but id like to try and understand what was happening in case it happens again. I was running both off a 1 Spot PSU, although i did unplug the BDDI from this at first but it made no difference. Thanks for any tips or replies.