The wonderful
Historia da Música electroacústica compilation.
This independently-sourced collection is a chronology of contemporary-classical electro-acoustic music. Ubu presently hosts the set for download, though I would certainly purchase a nicely-packaged box set if one were made available. (Sadly, it would likely be a logistical copyright nightmare).
For those hungry for even more, there’s also a great Youtube playlist of 391 tracks called “Electronic/Musique Concrète/Tape Music/Minimal/Abstract/Ambient (10’s – 70’s)” by user guernica0206