I do a lot of rock concerts as a soundman in my home town. Usually between 3-6 bands play, so not everyone has a chance to soundcheck. And very often there's no check at all because of time, and I have to use the first band as the soundcheck.
I also play a lot of shows like that as a bassist, so I'm familar with both sides of the situation.
Usually if a scenario like the one in this thread comes up, I have to choices:
1. Say to myself "crap in, crap out" and just let the band sound like ****.
2. Do something about it.
I usually use my mic (I ALWAYS make sure I have a mic sent to the monitors, so I can easily communicate with the bands on stage during the show) to try to tell them if there's anything wrong. But sometimes it's actually a lot easier to just get hands on. Because if they play on rented/lent equipment (especially if it's from the company I work for) chances are, I know a bit more about it than them.
Like we have one of those Warwick Quad amps which I HATE

And I know from past experiences that if you've never touched one before, you need some time to figure out all the buttons and that weird matrix thingie.
Hmm. Now I'm just ranting
My point is:
Maybe the soundman was rude, and he could have handled it differently, but still. He's just trying to make you sound good, and you turned up after being told NOT to. Those Ampeg 8x10's is pretty powerful, and can easily carry the bass in a club without any PA support.
Did you ask for more bass in the monitor? And you could have tried to eq in a bit more high mid so you'd get more attack and at least heard that. Because if you turn up the master, you also turn up the mud.