Well, I've spent the entire morning listening to other people's music choices and I gotta say - Thanks. For the record: Shostakovich, Stravinsky, all things Russian: My mother is a classical violist. I grew up with wall-to-wall Russian composers. I love me some Mussorgsky (much better when it isn't Emerson, Lake and Palmer), love me some Stravinsky (Firebird is a fave), love me nearly everything Russian. I oughtta pick up some Shostakovich 'cuz I don't own any; my wife isn't fond of the Russians 'cuz they're a little too "mathy" but I think they're great. Charles Ives: Pleasant enough, but not particularly memorable. I shall marinate in it further. iTunes is great for this. Ligeti: Pioneer or no, he's got that "I'm just fucking around with synthesizers" vibe which was pretty cool back when nobody had ever seen a synth before but I kinda feel those guys were assed out the minute Walter Carlos got on the scene. Hell, the Barrons kinda shut the Ligeti school down as far as I'm concerned: The Ligeti school is also well-represented amongst Kyma users. It's just too easy to do things that aren't musical when your stuff doesn't lend itself to music. Shoenberg: Awesome. Have heard before, will hear again. Boulez: Everything I hate about Philip Glass, I hate about Boulez. Stockhausen: The rivetheads have been worshipping Stockhausen for 30 years. I've never gotten into it, but I probably should. Ensturzende Neubauten owes a lot to the guy; I have a hard time listening to a lot of Neubauten, though. Wanna see something awesome? Know why it's awesome? 'cuz it's 4 solid minutes of '70s era Laurie Spiegel in a tween summer blockbuster.
This might or might not be up your alley, but I totally forgot to include some Musique Concrète: Pierre Schaeffer: And speaking of schaeffers, there's also R. Murray Schaeffer, who sometimes writes not just for instrumentalists, but also the environment - allowing nature to interact with the musicians, or placing the musicians around a lake to take advantage of the natural reverb and echoes Steve Reich is another composer you might dig, if you've never heard. I wasn't sure if you were looking for earlier stuff, so I kept to the last 100 years-ish.
The Musique Concrete guys are a little amusical for my tastes, but I appreciate what they do. So I typed "steve Reich" into my iTunes to see what comes up - I have a bunch of ambient weirdness from backintheday that I bought in bulk and I don't always know what it is. One song came up: By damn.The song also uses a harmonica sample from Ennio Morricone's The Man With The Harmonica (from the film Once Upon a Time in the West) and parts of Electric Counterpoint, a piece for multitracked guitars composed by Steve Reich and recorded by Pat Metheny. Reich was "genuinely flattered"[8] by The Orb's use of his work and instructed his record company not to sue.