Chris, it depends on the soundman.

If you've played in a band, you've probably been screwed over by a soundman at some point. The band I play in (as opposed to the one I do sound for), me and another bloke swap the bass around, and the one that isn't on bass plays his own guitar. I also play violin occasionally. We've changed instruments before now and started a song to find that one or other is still muted. OK, it's harder for a soundman to keep track of this, but that's what they're being paid for. And if you know the band's material, you know what to keep an eye out for.

Another problem, as Richard says, is *listening*. A local folk club used to run a small PA rig, and we had a soundman who was literally deaf (hearing-impaired anyway). He practically ran the club into the ground by constantly messing with levels, getting howls of feedback and all the rest, before the organiser decided he'd had enough and chose to make the club acoustic-only simply to get rid of the guy. And a few years back at Broadstairs, there was a fantastic duo playing drums and acoustic guitar where the guitar was practically inaudible, and in spite of asking the duo in the interval to get him to do something about it, he simply didn't (and the duo said they didn't want to push it because he could be touchy when asked to change stuff). A great gig spoiled.

Graham.