Outside of this being PIC based.. how does it differ from the RuggedCiruits Audio board they have out? (curious is all)
Well, that is the main core of the difference really.
The RuggedCircuits one uses the ATxmega32A4. That is an 8 bit chip, just like on the Arduino itself. Yes, it has a DAC on-board the chip, but it's only 12-bit, so unless RC are using an external DAC of some form, even 16-bit WAV files will only play back at 12 bit resolution. The dsPIC, in comparison, is not only a 16 bit controller (with all the associated benefits that come with that), but has a 16 bit sigma-delta (audio) DAC on the chip, so you get the full 16 bit resolution out of 16 bit WAV files. Not only that, the dsPIC has a DSP module in it, so complex filtering and other intensive signal processing can be performed (the firmware doesn't do this yet, but it could).
Have you worked up any code examples or libraries for it?
The site for the board is at http://sf.net/projects/wavepro
and there is a library available there to download. It's a fully open-source project, so you could have a go at building your own - schematics are on the site there.
I am curious if you can:
1.) layer/mix audio sounds? (ie: having a back ground track playing.. and layer/mix other sounds/samples over it?
Not at the moment - it's single sample only at the moment - however, it is in its infancy, and multiple sample playing may well be on the cards.
2.) SEAMLESS looping?
Again, not at the moment, but as before, it's something that could easily be added to the firmware if people want it, so it may well happen.
I'll drop you a PM to get your details.