I'm curious if OP has tried advertising on some of the torrent sites, where people are currently sharing thousands of songs basically for free? Offer those people a chance to make $$ from something that they are currently doing for free, and I would guess you could get some takers.Then again, that might be problematic for artists/labels who have a beef with torrents? Lol ...

Your project looks interesting. Biggest problem for me is that I don't want to leave a PC on and connected to the internet ... I don't want to personally provide that caching service. My preference is to be a passive investor. So it doesn't seem like it makes sense for me to participate. Not to mention it will be an illiquid investment in an extremely high risk venture. Worth watching for now perhaps.