Sure, I would say HP50 has a much wider soundstage, more smooth midrange and natural bass sound, treble is clear and not "sparkly".
The M500 is much brighter and faster, very exciting to listen to, you kind of feel the energy more although the soundstage is much narrower and there is a slight dip in the treble.
Which is why I think it is hard to say which is the better headphone, you really need to listen to both to explore which sound you prefer
Oh no, I think the HP50 and M500 are very different, I have them both, but I must admit I like the M500 more, why?
The M500 is much more comfortable, the sound is more dynamic and I like the rounded treble, makes bad recordings sound tolerable. The HP50 is more neutral and more "correct", but the M500 is more fun to listen to.
Soundstage is best on HP50, no doubt, which is the biggest plus to the HP50 compared to M500.
Build quality is much better on M500, really feels well made. HP50 is just plastic.
Thanks for the replies, guys! Guess the M500 is more for me since you say it's more "fun" in the sense that its slightly warmer/bassier.