I can definitely say the Ultrasone HFI-780 is a very balanced and to me natural sounding headphone. It has detailed treble with a bit of sparkle and a eerie large soundstage for a closed headphone though not on the same level of the Audio Technica ATH AD700. The bass is strong yet blends in with the treble perfectly never getting in the way of the crispness. I have been using the HFI-780 for about a week since purchasing and in that short time it has become my go to headphone for movies with crystal clear dialogue and heart leaping explosions. Music especially ambient, electronic, industrial, heavy metal and classical are all fun and fast. Games I can hear every little detail in the environment with depth and down to the last sonic tone with a sense of balanced distance where the soundstage doesn't feel overdone in rpgs such as SKYRIM or like a cheat in shoot em ups.
For spacey way out electronic sounds like Delia Derbyshire music or the sci-fi movie classic Forbidden Planet these headphones are killer. This is also the reason some may consider them a tad on the metallic unnatural side. Definitely not warm but the balanced combo of crystal clear treble and stomping bass make for a very fun alive audio experience which feels as if nothing is missing from the band. A completeness of sound I don't find in many other headphones which may shine on some things but not on others.
Excellent headphones am really happy I purchased.