Err...
George Perle!
Hey! Straight off the tips of your fingers you bring up one of my personal favorite, but rather little-known, "modern composers". He developed a 12-tone system that actually had a modern, atonal, but generally easy to listen-to style. My composition teacher (I believe) had studied with Perle (and Crumb, Rochberg, and others), and I was quite amazed how natural his style flowed, rather than fighting with 12-tonality, Perle found a "naturalesque" sense of tonality that just seemed easy to appreciate on first hearing. His wind quintets are quite remarkable.
While stylistically quite different, there are similarities with the music of George Flynn, using tone classes that fall between the (often) harsh clashes of strict 12-tone or serialized constructs (e.g. Boulez 2nd Sonata, or Barraque's Piano Sonata), and the last remains of tonality (explored by Scriabin and friends, including early Schoenberg).
I guess what I'm rambling on about is that people interested in the roots of "modernism" should take a look at George Perle, and how he found a place for all notes, not exactly "equal rights", but properly distributed throughout a work. And blaaablaaablaaa. Good evening, friends.
L.