I was at the Gothenburg hifi show last Saturday. There I listened to these earphones.
They sounded really good and they will be sold with an iOS DSP correction app.
It will cost about €70 with the app. I got to try them with and without dsp engaged.
Without the DSP they were neutral with good bass. With DSP the bass got a bit more
detailed and the soundstage expanded. I can only compare them to my
Sennheiser HD 25-1 II and they are really close with the HD25 a little varmer and the
XTZ has more bass.
They will start selling them in a couple of weeks. XTZ sent me this link to a pdf about them.