[Balloon] Audio input front end..

The only changes I can see that are missing are:
Increase C108 & C109 (in fact up case size to allow 10uF caps if
needed).
Although 1uF will probably be good enough.
Mark R19 and R20 NOFIT (if not already so).

I've also got audio recording working (at least to the point where I
think it will work) A new CPLD release will turn up in due course...

David