「not any」と「not just any」の違いは何?

Yesterday I went to a performance in the early evening. Here's a link to Japanese information about the event:

http://www.cmflg.com/cmflg090927.html

The performance was only electronic music and video (notice the difference between "not any" and "not just any").

× There wasn't just any rock music.
○ There wasn't any rock music. <- this means you couldn't hear rock music at the event.

This photo is of a Belgian musician named Yves De Mey.

× He's not any electronic musician.
○ He's not just any electronic musician. <- this means that I think his music is kind of special.

• not just any ただ普通｛ふつう｝の～ではない (definition from Eijiro on the Web)
  

He's a muscian whose mixes I've been listening to lately. Here's one approximately one-hour DJ set he performed. If you are curious, listen to it.

http://modyfier-modifying.blogspot.com/2009/09/blog-post_11.html

Listening to live music was a nice way to spend my Sunday evening. I wish I could do it more often. I hope you all had a nice weekend. Study hard this week!