Great website! Very edumacational. My hardware is MUCH simpler. The low pass Nyquist filter is done in software with only a few lines of code. It's really just oversampling. For a Mic preamp I used the chip I mentioned above with a few external parts. It has many advanced features. Alternatively I interfaced to a PC, iPod, or stereo using a variable resistor only. That is how you adjust the DC offset. You can adjust the gain for testing using the volume control. You can sample at 32khz if you want, but in your case obviously it is not needed. Keep up the good work!