I could have reconciled the description with the image if it had been square. I've been on concert stages a few times, so I get how they look, but..
I've never seen one that was outright circular. I've seen one that had a circular "bulge" that let the singer get close to the crowd, and then long, rectangular "wings" where the guitarists and stuff would play, with the drummer (or DJ in this case) in the back. That's also fairly common for orchestral stages, where the composer is on the circular outcropping of sorts. But that's not what Vin's describing.
So I have no idea what this stage is supposed to look like other than DJ platform, crowd, and circular. Are there walls on the sides? Curtains? A backdrop wall or amp stack wall, or what?
I mean, here's a shitty representation of what I THOUGHT it was:

The rounded rectangle thing is the DJ stage, with the second line being the backdrop wall that you typically see hiding the amps and what have you. The double lines are stairs.
This is the sort of "winged" stage you see with certain orchestral shows, or with some metal bands:

Again, pretty shitty, but there you have it. The second line is like.. curtains or a backdrop wall, like before.

And that's what I'm getting out of Vin's description.. but it leaves me with questions. The dotted line is sort of where I'd assume there to be a backdrop wall, but are there walls on the side? Is it some sort of strange open-air stage? Or what?