Looking at the Line6 video "Gigging with the Firehawk 1500", it looks very simple and easy to plug in an XLR lead from a mic and then to the pa/mixer. However, when I tried it alI I got was an annoying hissing noise. I changed the lead for a newer XLR mic lead and got the same again. Am I using the correct lead? Should I use and amp XLR lead or am I missing something. Also, there are 2 XLR outputs, do I need to connect both or is that simply an option. Apologies if this sounds like a newby question, but I am... a newby! :)