Rant warning
I have lost count of the concerts I've walked out of because it was so loud I could not hear the music but instead felt that I was being assaulted by noise. Unfortunately there just seem to be a large number of Sound-Techies who cannot understand the concept that just because the rig can be turned up high enough to shake plaster off the walls does not mean that they should. In many smaller venues they still seem to set it as if they were trying to fill a football stadium. Perhaps as someone already posted it's because they are deaf or it may be that they work most often in certain other types of music where the words are so banal that it makes little difference if they are heard or not and it needs to be loud enough to be heard over their audience who don't shut up to listen.

Rant over

On a good note I thoroughly enjoyed a (non-folk)concert we went to last week. The Moody Blues played the Albert Hall it was really good, the sound filled the place but at no time was it uncomfortable and it was balanced so that you could hear all the lyrics.