I have a suspicion the audio routing is different between Mango OS and Mango app. I use the dx220 primarily with Hugo 2 feeding it over optical. Similar differences heard from the HP out between the two Mangos are also present using external DAC. Reasons why I think audio routing is different (1) no mqa unfolding on Mango OS (2) Mango OS allows you to put EQ before the optical out. Android app does not. This actually means the output over optical is NOT bit perfect. I'm wondering if there's some always present sample rate conversion on the Mango OS implementation. Hoping iBasso can clarify. For lossless file formats, the difference cannot be explained by supposed timing or supposed software algorithm differences some claim here, I don't buy that for a second. Timing is inherent in the bit stream and can only be modified if resampled before the DAC stage.