Sounds like the CHIP guys are desperate for use cases. That LePai amp already plays MP3 off USB and SD card.
The thing that really got me was their aim of being entirely open source. I like the Pi, but there's a lot of stuff closed off.
I think the popularity of the Pi has helped there.
(The adapters are great, but depending on what you're plugging in, you may need to supply power as well. A microUSB cable is included in the box. If what you want to display has HDCP, that needs to be removed before the adapter.)