Just had a little bit of time to sit down and to compare HP150 to M50x, two distinct sound characteristics.
M50x is balanced with enhanced bass and smoother/warmer mids where treble doesn't extend as far as HP150. On a contrary, HP150 is balanced (somewhere on a borderline with neutral) with more upfront mids and more analytical sound in comparison to M50x. HP150 has a great mid-bass fast punch, but sub-bass doesn't extend as low as M50x and overall bass has more clarity than quantity. But make no mistake, HP150 has a PERFECT amount of bass, just it's not enhanced in comparison to M50x. Overall, M50x sounds warmer in comparison to a brighter HP150, and as a result upper mids/vocals in M50x sounds smoother while in HP150 they are brighter and more detailed. Also, HP150 has a much better soundstage, in every dimension in comparison to M50x.
I'm not a headphone person, but rather into IEMs. Also, I usually prefer enhanced bass and moderate brightness. But with HP150, I can't put them down, especially paired up with E10k from my laptop. Btw, those are available on Amazon: http://www.amazon.com/SoundMAGIC-HP150-Premium-Folding-Headphones/dp/B00LV8TR54/ and MICCA store is the official distributor of SoundMagic so warranty will be honored.
Should have a full review in a few days.