I wish you would make your point clearly.
Are you trying to say that he hated the noise of some previous concert, so he started planning to shoot up a crowd at some different, future concert??? That sounds more bizarre than anything we have heard, although I admit that there does not seem to be any good explanation so far.
Are you trying to say that he hated the noise of some previous concert, so he started planning to shoot up a crowd at some different, future concert???
...
Yes, I think he lived in hotels when he was in Vegas, so he probably experienced many of these concerts.