Rob and Russ, I've been using the IDC devices for about 15 years, but I'm trying to minimize silicon and real estate to the maximum extent possible. Luciano hit the nail pretty square on the head with his Atmel applications note...

Since the PIC I'm planning on using is doing about ten tasks at human speed ranges, my thought is to proceed through the ten tasks in order and when the "record" button is pressed enable an interrupt every 50 microseconds (20 kHz.) to do a sample, then return to the proceedings of the ten tasks. WHen the "playback" switch is hit, simply dump the contents of memory into the d/a converter (i.e. low pass filter) and sum the playback audio with the other audio sources in an opamp.

Speaker/phones audio is not necessary. I reduce all audio inputs to line level (1 volt/600 ohms) before I condition them, then provide them their own compsymm phones and speaker amplifiers.

However, any "don't go there" comments would be well received. I've reinvented too many wheels in my career.

Russ, I had forgotten that back in the '50s, I too was a "WN6BHI" who became a WB6BHI then went vanity call with WX6RST about ten years ago.

Thanks fer yer help...

Jim