Someone pointed out why the vocals are always louder on the webcast: because they're always louder in the room's PA. That's because there are things on stage like guitar amps and drum kits. Those are loud. So the vocals are louder in the PA to compensate for that. Meaning, sadly, this is not something that can be fixed with a webcast-only EQ setting: the only real way to fix it would be to have a webcast-only mix, which would be prohibitively expensive (we'd need to have another engineer and another board to do it: it would not be the automated affair that our webcasts are now.)
One second-best way to fix it would be to do the webcast not from a mixing board feed, but instead, from a microphone in the room (this would also bring in more crowd noise, which would be nice: right now, the only applause you hear between songs is that which the vocal mics pick up.)
That would work well for Real Bands, but wouldn't work as well for the kind of Karaoke acts we get most of the time: bands whose entire act is coming off DAT are going to sound better if we have the raw feed, without an air gap. And the same is true of "live PA" acts (which is what DJs call themselves when they try to pretend they're in a band instead of just doing mixing of prerecorded material.)
In other news, the Icecast server keeps hanging. I don't know why; it's been up for 45 days, and nothing seems out of the ordinary on the machine, but I've had to restart it three times in the last 48 hours. "Maybe rebooting will fix it."