I cannot help feeling even more like the center of the universe than usual as I walk along to a rapid little version of "The Way You Look Tonight" (27-30)
This music is making the speaker feel really powerful. Of course, we all feel like the center of the universe, because we only see the world through our perspective. But by saying that the song makes him feel "even more/ like the center of the universe," the speaker suggests that the music gives him a heightened sense of power and importance.
and all I can say to my fellow pedestrians, to the woman in the white sweater, the man in the tan raincoat and heavy glasses, who mistake themselves for the center of the universe – all I can say is watch your step (31-35)
These lines give us a sense of the speaker's cockiness and importance that he experiences as a result of listening to the music. The pedestrians he's passing sure aren't the "center of the universe"; he is. The speaker, in other words, is feeling very important as a result of listening to this music.
And if any of you are curious about where this aggregation, this whole battery-powered crew, is headed (41-44)
By describing himself as part of an "aggregation," the speaker suggests that his sense of power comes from belonging to this group of musicians: he's part of a gang. We'll also pick up on the word "power" in "battery-powered crew." The speaker is referring to the batteries that power his CD player here, but this is not only a battery-powered crew, it's a powerful crew.
[…] let us just say that the real center of the universe, the only true point of view,is full of hope that he, the hub of the cosmos (40-44)
The speaker uses some pretty extravagant terms to refer to himself in these lines. He's the "only true point of view" and "the real center of the universe," and the "hub of the cosmos." It doesn't get much more self-centered than that, does it? But the speaker isn't being totally serious, of course. He's just trying to give us a sense of how good this music makes him feel. It makes him feel like the center of the world.