I thought that podpress had this feature but I must have been thinking about a plugin I used years ago. How hard would it be to add pre-appended audio to podpress? This would be very useful so that a separate "jungle" or "intro" to the podcast could be uploaded once and then automatically played before the main file.
I know the WP Audio Player plugin has this and another podcasting software I used a long time ago had it too. What do you think?