Depends on your source and amp driving the HD800. I also prefer a basic Lambda setup over a mediocre driven HD800 except for classical and orchestra which the HD800's just annihilate anything on. Given I've heard my HD800's on some TOTL amps I can say it is very nice and a level ahead of the Lambdas. Wouldn't use the commonly used hyperbole of night and day different as they both have an airy presentation.
PS Headfi mobile is broken as schitt.
My 800 rig is:
800 with silver cable..
Taboo mkII ,Metrum dac,jriver18.all flac files.