We didn't change anything regarding that though. From 4.2.0 we play some silence at start-up through the official Android driver, which is the only thing I can think of that may have influence.
If you leave all flags disabled and format on Auto, then you get what the app thinks or knows to be the best (and often only) setting for the device.
Play through Android is there for historical reasons and has no influence when using the HiRes driver.
Seems like that's what did the trick,