I received my burson few hours ago and honestly i wished the m-stage was there up to its level so i could return it and my wallet would have been happier.
It's in a different league honestly, soundstage wise it makes the hd650 shine like never before. Not a hint of 'sennheiser veil and a quite surprising treble extension up there.
It looks beautiful, feel like ultra high-end quality and will steal alot of my listening time for the next weeks.
M-stage on the other hand was great for it's price, but i'm glad i've upgraded.
I might just keep it for my computer setup anyway, at least a use for its dac