If you are interested in exploring further along those lines, and want either a high quality (& free!!) download or simply to research and sample-listen prior to purchasing LPs, definitely check out this website, which is a serious attempt to archive important 'new music', contemporary classical, etc. They have Kagel, Subotnick, Parmegiani, Hindemith, Babbitt, Cage, etc.
http://www.avantgardeproject.org/archive.htm
http://www.avantgardeproject.org/archive.htm