I think Danny Spooner is the loudest I've heard, with a voice that would peel wallpaper - and no, it certainly wouldn't put me off having him at my folk club! He's great - and a really nice bloke too. He was going to be on at Sandra's club The Loaded Dog next week, but he's gone and went and broken his leg. To quote Sandra:

"Danny Spooner has gone & broken his leg while bushwalking. For some reason he thought that 3 pins, plaster & crutches would stop him climbing the stairs at the Dog. I told him we would help him up the stairs (bump, bump, bump) but he decided he'd rather come back in August"

For a close second in the loudness stakes, my own John Warner (mudcatter jack halyard) would have to be right up there! He sang a collection of new songs at my folk club in December, which showed that although he can belt out a song and drown out most of us, he is also capable of light and shade when it is needed in a more sensitive ballad - and I'm not just saying this because I am biased ;-)