[vk93]

Are there any places selling this amplifier, or do I have to get lucky and find someone who happens to be selling it?

 

[K_19]

Dedicated Headphone amps are not exactly items that you can find at your nearest electronics store, unfortunately. They're usually available for purchase online at websites of the makers, or you can find them second hand here in this forum.  Audio-GD Compass has been discontinued for a while now, and has been replaced by a model called "FUN".  You can still find a pre-owned Compass on sale here quite frequently however.

 

[vk93]

What are the differences between the fun and compass?

 

[desktophifi]

You'll get more replies at the Amps section. 

 

[K_19]

I've never owned the FUN, so I couldn't really tell you, nor is this really the appropriate place for that discussion.  However, there is a thread dedicated to it in the Headphone Amps forums which will surely outline the differences, so you can have a look through there.