@Yehudayona
The baal hasimcha whose request the volume be lowered by the band is refused has a bad contract. Having married off two daughters in the past 16 months the contracts I signed had a clause added by me requiring the band to adjust volume as instructed by Mrs. CTL, the Kallah, Chason or me. I told the booking agent, either sign the contract and adhere to it or I’d spend my money elsewhere.
It is not the responsibility of the baal hasimcha to help the band get other buisiness.
Personally, if a band leader ever refused to lower the volume at a simcha where I was paying the band, he’d be told he had 2 alternatives, lower the volume or pack up and leave with final payment (and be on the end of a lawsuit). The lawsuit being just a threat…a frum band leader would be taken to a beis din.
NO baal hasimcha or kallah should be intimidated by any wedding supplier, they work at our pleasure, they don’t run the show.