And if any of you are curious about where this aggregation, this whole battery-powered crew
When the speaker refers to "you" in these lines, it's not absolutely clear to whom he is speaking. It could be the pedestrians walking past him down the street. It could be us readers. Most likely, it's both the pedestrians and us readers.
The speaker refers to himself and the jazz musicians he's listening to as "this aggregation,/ this whole battery-powered crew." An "aggregation" is a something that's made up of different parts. Indeed, each person in this group of five—four musicians plus the speaker—serves a different function. The musicians are each playing a different instrument, and the speaker is listening to them.
By referring to himself and the musicians as a "battery-powered crew," the speaker references the fact that he's listening to some sort of CD player or Walkman. (Do we even know what the heck those are anymore? CD players and Walkmans are battery-powered. You couldn't just charge them up like you can do with iPods.)
is headed, let us just say that the real center of the universe,
Here the speaker clarifies what we (and the pedestrians on the street) are curious about. We're curious about where the speaker and his crew of jazz musicians are "headed."
The speaker again refers to himself (and his jazz musicians) as the "center of the universe." They're the real center of the universe.
The speaker is being hyperbolic here. Of course, he and his crew aren't the real center of the universe. After all, all of those other pedestrians he's walking past also feel like they're the center of the universe.
The speaker knows this, but he exaggerates in order to give us a sense of just how powerful and important he feels listening to this music.