Hi,
the headphone quality is the best so far from any Xperia. It's a little bit louder than the Z5 and Z3 series. I compared it to the LG G5 and the Samsung S7 series and the Xperia X outperforms both easily, even with the B&O add-on for the G5. By the way, the sound quality of the X and the X performance are absolutely the same.
The sound signature has changed. I was coming from the Z3 series and the sound there was a little bit leaned back and thin but with great tonality and sense for rhythm and speed. The sound signature of the X is characterized by a snappy, forward sound that’s crystal clear and lighting fast. The sound is bursting like sunlight off the hood of a shiny-new Corvette. It's full, vocals are drawn very realistically on the virtual soundstage, dynamics and stereo image are astonishing. I thought I was a fan of the subtler, warmer sound I heard from the Z3, but those who hold sharp clarity in the highest regard may edge towards the Xperia X experience like me.
Hints:
- Turn on DSEE HX, leave everything off
- Use automatic headphone compensation with medicore headsets only.
- Get a decent set of cans like the Sony MDR-1 series
- No need for the Sony headphone USB DAC PHA-1a, get the PHA-3 to improve the experience even further but don't forget to invest in really good headphones like the Sony Z7
