I dont agree, the firmware is changing the sound quality on a technical level as it is lowering sound distortions. This is making the sound smoother, increasing detail, naturalness, transparency, texture, timbre, separation, everything is improved, there is no way I would call it a tonality change, its a sound quality upgrade, no other way to put it, and enough of a difference to change its rankings among other DAPs.
As much as i love the sound i am not hearing more details or more clarity and that is with some of the best universals like sennheiser ie800 and shure se846.