Here are some excellent avant garde works...i dont have much of a back story on these fairly obscure composers, but these are all REALLY WORTH LOOKING INTO....if you like that kind of thing
Mauricio Kagel
"Phantasie fur Orgel mit Obbligati"
1967
excellent organ piece that is pretty out there on the great deutsche grammophon label
Roberto Gerhard
"electronic explorations from his studio + bbc radiophonic workshop 1958-1967"
2014
wild spoken word tape piece
JK Randall
"computer music"
1965
can't find the date for the record but this piece is from 1965. the only American on this list.
Swedish Contemporary Music
This is by far the best piece on this compilation-by Tommy Zwedberg "hanging" 1979
i hope you liked my post!