Paul Stoffregen posted an update in his Teensy Audio Library on Hackaday.io:
TDM Support, For Many-Channel Audio I/O
Some projects need a lot of audio I/O. Maybe you’re doing positional audio sound effects (using the 8-tap delay effect) where ordinary stereo or even 5 channel “surround” isn’t enough? Maybe you’re making the ultimate Eurorack synthesizer module? Or you just want a lot of signals, because you can!
Here’s a board for the Cirrus Logic CS42448 chip, which provides 6 inputs and 8 outputs. All are high quality audio, and all work simultaneously.
PaulStoffregen has shared the board on OSH Park: