My whole site is 100% K2 powered.
godsstream.com/
I haven't seen K2 used in this way before. Needed the all videos reloaded instead of all videos as the user interface (mp3) with avreloaded is much better for me.
Audio files are uploaded as an attachment by the user and then they can easily find and with (av reloaded)insert player with out help.
I am very happy with K2 there would be a couple of additions on my wish list.
But mainly better mp3 support.