Just for posterity, I will leave my review of this device.
The analog audio output is at least 15 dB too low. I built a 15 dB
preamp as a workaround, and that's fine. Just turning the volume up on my power amp just raised the noise floor unacceptably, but with a preamp this isn't a problem. This problem does not affect the optical output, so it's clearly some sort of design flaw in the analog output stages. As others have noted, the digital output is 16 bit 44.1 kHz. Run through a good external DAC (I
built one based on the PCM1793) the sound quality is as good as you can expect. Running the output from my "good" DAC into the analog input of my AirPods Max yields audio that is indistinguishable to my ear from the same audio streaming directly to the APM over BT.
I had to try the initial connection a few times before it stuck, but since then it's been perfectly reliable. The connection via our home WiFi is far, far more reliable than the old bluetooth box it replaced.
The only other issue I'll mention is that this box is the same price as a HomePod Mini, but has no Siri functionality. That, in my opinion, makes it overpriced. If it were more like $60 instead of $100, I wouldn't have an issue.