It was rumored to feature Dolby Digital Plus surround sound and an HDMI output for media playback.
The Xperia X7 was intended to be Sony Ericsson’s flagship entry into the ecosystem. At a time when the brand was transitioning from Windows Mobile to Android, the X7 represented a high-performance alternative that ultimately remained a concept or a prototype. Rumored Key Specifications Sony Ericsson Xperia X7 Review
The cancellation of the X7 marked a turning point for the company. By , Sony acquired Ericsson's share of the joint venture, ending the "Sony Ericsson" era and focusing entirely on the Android-based Sony Xperia brand we know today. It was rumored to feature Dolby Digital Plus
It was built to run Windows Phone 7 , featuring the then-new "tiles" interface. Why It Matters Today Sony Ericsson Xperia X7 Review