I've been listening to the post-rock keyword on archive.org for a week now. I'm going to split my search results down to a few posts, starting with these tracks which are not part of bigger releases:
From Delta Waves Under Clouds Over Ground release on Earth Monkey Productions:
And also a track from a Gasgiant release on Floppy Records I stumbled upon a while ago... The Silent Ballet raves about Gasgiant in their review.