My fairphone 4 arrived and I tested the Apple DAC with the special thingy I have for my hearing aid that functions as a wireless microphone/jack-equiped sound streaming adapter.
I can’t yet comment on the quality, but I can say that the maximum volume was way too low. Much lower than the maximum I can get from a phone with a headphone jack. So low I couldn’t hear the subtle parts of a song.
I solved the problem by downloading a headphone sound booster app and increasing the maximum.
I think the problem here is that the default maximum for USB C audio out on android is set too low, it appears to be a common problem. The fact that such booster apps exist seems to support this theory.
I will do more testing and report back if I find evidence to the contrary.
If anyone with other brands of usb-c to audio adapter wants to check this, simply see if the maximum volume you can set when using the adapter is lower than when using the same listening equipment (headphones, earbuds, speakers, etc) on a phone with a headphone jack. Take care to not hurt your ears! 