A couple of updates to my review posted yesterday. Added the following to the review this evening after some emails from Aune:
RE. Digital Out: Aune are currently working on an external docking connect through the Mini HDMI port, which will bring digital output capabilities (Coax, AES, I2S, etc.) via a receiver module to high end DAC.
RE. Battery Life: Aune states that the M2 is Class A music player, with voltage greater than 500MA, and that a compromise had to be made between a Class A/B device with 8 hours of playing time, and Class A with 6.5 hours. The decision was made to sacrifice playing time for better sound quality. With daily charging, 6.5 hours battery life should be enough for regular use, and external power packs can be used to extend this if necessary. Several hours later I got another another update saying that the battery life on the production models has been upped to 7.5+ hours. Not clear yet if that's a FW tweak, or if they've done something with hardware.
Good news nonetheless, and part of the fun (?) of reviewing pre-production models.