If I understand correctly, DSEE HX is an additional algorithm for use with LDAC, that Sony implements solely into their newer models, i.e. I have not seen 3rd party model (Ldac receivers and Ldac headphones of other brands) to state in their specificarions, that it is used. Sony says it is not just an upscaler, but to simplify it, it upscales and by it I mean it calculates missing information, that was lost somewhere in the process of encoding music into lossy containers (all of them are lossy, even those losless ones, as digital is no analogue...). Not as advanced and true as Chord’s tapping into music data for decoding it faithfully using brutal computing power (more taps = more precise identification of transients = better sound), it probably cleverly calculates (creates) missing pieces of information and it probably uses fle metadata / Ldac metadata / its own metadata identified during frequency analysis somehow to identifiy frequencies that need recalculation most. Maybe similarly to Chord’s brand new M-Scaler. And to that Shanling’s response: Headphone manufacturers tune their dacs to sound best with their cans lately, Take f.e. Audeze iSine and cypher cable (that contains dac) - both units are tuned to sound best together, much better than with other dacs. Is it a fair thing to do? In my opinion it is not. If you do this, then sell it only together, right? it is kinda similar to preimplementing Chrome into Android devices or Internet Explorer into Microsoft Windows. It makes that product less usefull for use in other scenarios. Yet it happens, and noone says a thing against it. That said, Sony may have implemented a feature, that it uses flat tuning when their cans are paired with sources, that licenced only something. Or maybe noone can licence it, maybe it is related to Big data collection through android phones - you want DSEE HX? Ok, then install our app, and we will give you DSEE HX . Same as with Audeze - noone says a thing about or against it. Secret stuff, I tell you. It is merely a guess. I may be wrong.. But I know one thing for sure: They do not want to disturb consumers with such an unimportant information . Manufacturers are so kind to us. So to sum it up. Noone knows for sure, and probably only way how to react is to say these things happen in the world of business, Live with it.