hm its a tricky one all right.

one really awful gig story, concerns one of my favourite artists - the late Lonnie Donnegan. He was with Monty Sunshines jazz band in a school gym. All of the brass players had their instruments right up to the mikes so you couldn't hear Lonnie at all in that cavernous space.

The way I see it . you have two options - either you get a bug for you mandola and plug into an amp with a decent sized speaker - or they play a lot quieter. Actually - perhaps it would be as well to do both - get a monitor as well, and then they will be have to face up to the racket they are making and aim for a balanced sond. If you have a monitor, it will give them some idea of what they are inflicting on the audience.