There are many positions that can, and will, be filled for the traveling musical group or artist. Although it is important that you become “Expert”, or “Known” in at least one particular field (Audio, Video, Back line etc.) it is also of utmost importance that you learn about, or at least have a working knowledge of all the other areas. (Audio, Video, Back Line etc.) Here’s an example: If you are a Backline Tech. (Guitar, Drums, Keyboards etc.) having a working knowledge of audio might give you insight into figuring a problem out more quickly. If you have an instrument – guitar, keyboard, etc., plugged into a D.I. (Direct Box, used for interfacing and connecting a 1/4 inch cable from instrument to a mic cable for audio.) and are having noise problems the first thing you want to do is unplug your instrument from the D.I. That cuts the problem in half, immediately. If the problem persists, then the problem lies past your equipment, and involves only an audio problem. If the noise stops, get digging, the problem lies at your side of the split. Try to perform this task with as little finger pointing, grandstanding, and accusatory words as possible, after all, we’re all there to make the big picture happen. Stick with the audio representative and let him do his job. Watch and see if you can be helpful in any way. I believe this to be an excellent starting point to figuring out these types of problems.