I just wanted to let you all know that I'm currently working on the second revision of the PCB; I have to fix a few things, all related to difficulties in properly soldering the board without the proper tools (read: missing reflow station or oven). I'm actually modifying the DFN/QFN packages so to have longer pads and exposed bottom layer pads to properly solder the heatsink pad under the chips. I'm also evaluating the idea of detaching the power section and the USB section of the circuit into a separate board, sort of a USB serial/LiPo charger/Intelligent power switch , three-in-one functional board; I really think this could be really useful for a lot of battery powered applications that need easy USB communication. Of course this may force me to have two separate boards, one for power and the other to break out the connections of the other devices.
In the meantime, I'm also evaluating different options for implementing a working version of the DDS routine; running at 16 KHz, the interrupt routine has to process 8 tracks in less 750 clock cycles, and I have to deal with monitor and Trellis update. That's tight. I think I gotta make some math.