I want to report that the Teensy 3.6 plus the Audio Adaptor board has worked out well for the Audio impedance measuring project. It is not done, but it is measuring impedances with good accuracy in the 10 to 10,000 Hz range. A summary of where this is at, including software source, is at

I was able to work with just "stock" audio objects, which speaks well for the library. Thanks, Paul.

Cheers, Bob Larkin