Doc-Z,
It depends on the size of the venue, how loud the drunken crowd gets, and lots of other factors. I've never measured the DB, so I cannot comment on that.
I have a rule, though, that seems to work for me. First, I never play so loud the audience cannot conduct a conversation. I play loud enough for them to enjoy the music and dance, but blowing someone's head off and causing hearing damage by cranking up the volume is just plain stupid.
Most of the people I've heard that were playing rediculously loud were people that either could not play, could not read an audience, could not sing, and could not entertain.
I've been to several weddings that used DJ's for entertainment and they continued to crank up the volume and tempo with hopes of getting the audience off their butts and onto the dance floor--it never works. The audiences at most wedding receptions consisted of individuals ranging in age from 50 to 70 years old. The only youngsters, 20 to 30 year olds, were a dozen or so folks in the wedding party and a few or their close friends. So, what does the idiot DJ do? Puts on some hip-hop and rap, cranks up the volume to where the windows are beginning to crack, drinks a pitcher of beer and takes off his tuxedo jacket. At the end of the first hour, most of the older folks have either left or moved as far away from the music as possible, the youngsters are plastered, and other than a few requested first dance numbers, etc, the dance floor remains empty.
As I said at the onset, buy the system from a retailer that has a liberal return policy. If you don't like what you hear, take it back for a full refund.
Good Luck on whatever you decide upon,
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)