Here's another way to do the audio demo thing:
I make each one specific to the client's requests. That way they are getting the songs they like. I make each one special in my studio and send it out with a signed, complete contract. This makes it easy to seal the deal. I also ALWAYS include a SSAE with every contract. If the client has to look for a stamp .... they have time to change their mind too ...... Hmmmm?