It turns out that there's really no difference in posting an audio of a record you own and posting a MP3 you own - i.e. in both cases you are illegally distributing it. I suppose in a way it's like posting the text of a book you own. Yes you own it so you can read it - but you're not allowed to distribute it to the world.
I ended up selling about half of them, even with two auction runs. So the remaining ones, I have to find time to post on my website and see if someone will buy them eventually. I just haven't gotten to doing that ... my backlog is absolutely immense right now.