I'm having some problems with reddi in live settings. I'm running signal from pedalboard into reddi which feeds foh mixer through xlr port. From thru I send signal to amp. I get loud low frequency noise from my amp (cab) no matter what position ground lift switch is in. I also use reddi for vocal recording where it functions alright, but I don't use thru port in that setting. Any ideas what could be wrong? It happened on different occasions, at different venues. Whenever I bypass reddi (from pedalboard straight into amp) there is no noise.