Is it possible for an Arduino Nano to control a Teensy audio board? I would have several sound files on the Teensy audio board via the micro SD card. Based on certain events, the arduino would send a signal to the Teensy to play one of the sound files out the audio jack. I'm sure there's no reason why it wouldn't work since it would just be about making certain pins high and low, but thought I would ask before making the purchase.
The teensy audio board is designed for the teensy 3.2 board (arm cortex m4 cpu) at 3.3 volts. If you plan to use your own audio library and can either run the Nano at 3.3v or use bi-directional level converters, then you may have some success.
My recommendation is that considering you are purchasing the teensy audio board, why not also purchase the Teensy 3.2 board.