Used to run DX300 Max with Neutron (on
@Whitigir 's configuration) and it sounded imo better than MangoOS. On the new kid, Mango is hands-down the winner over everything I've tried so far (Neutron, with the same config, and Sony Player): absolutely dark background, heavier but still clear and articulated sub-bass, massive holography, a slightly warmer sound than DX300 Max but no less detailed with great separation of instruments. I'm not equalizing, just using D1 and DSD high on on Ultimate mode. Was quite disappointed at how Neutron sounds with 320Max, even emailed Dmitry about it as I had thought it was not properly configured. Neutron, don't know how to say it, sounds more artificial, more removed, not as spacious, almost tinny. Even on <$100 iems (my Dunu DK4001 is on its way to Taiwan atm as the left-hand side won't work, and I'm waiting on a pair of Moondrop Variations) MangoOS lets you in on a glimpse of what the device can do!
Of course, this is all subjective, I'm well aware that others' mmv and I'm not using cans, as my main use for 320Max is on the go (I find its size and weight not an obstacle to mobile delight).