So at the end of the day - I guess my real question is whether or not anybody knows if the extra $50 spent on the Fidelio X2's vs the M560's translates to a better overall sound and bass - Or if the Fidelio is an overall better pair of cans. It seems like they're both really solid in the build quality department.
I'll be honest - the sound leak on the X2 is bothering me less and less as time goes on. It hasn't turned out to be a deal breaker as of yet. I was concerned at full volume it'd be so loud it'd wake someone if they were in our guest room but I don't think it will.
Bear in mind that I haven't heard the M560's--and I definitely have heard the X2's.
So I went back and reread some posts here about the M560's:
Post #173 & 177
http://www.head-fi.org/t/820107/monoprice-monolith-m1060-and-m560-planar-headphones/165
My very first reaction was: wow pretty bright; peak in the highs; sibilant, harsh (I think the same thing about stock HD800's)
I think with them being so bright, the rest of the spectrum seems low. The mids are OK, but missing lower mids or body.
The bass is extended, but again just not that much bass. So the net result is an overall "lean" sound.
The thing is, I have to turn down the volume so the highs don't hurt my ears... If I listen to say piano or acapella singing, then the mids aren't bad. Still not enough bass, but they sound OK.
Post #184
http://www.head-fi.org/t/820107/monoprice-monolith-m1060-and-m560-planar-headphones/180
Post #200
http://www.head-fi.org/t/820107/monoprice-monolith-m1060-and-m560-planar-headphones/195
I didn't keep going. It may well be that they sounded a lot better when finally burned in...
What I can say is that the Fidelio X2's are well known here for great build, good soundstaging, and a relatively warm/listenable sound quality. They're not state of the art detail- or treble-cannons, but if they were, I wouldn't own them. I really can't think of another big-name headphone that is the total package the X2 is. And you already own them (no small thing).
By comparison, the M560's appear (at best) to be a sonic work-in-progress. If they sound better burned in, still, they're probably brighter than the X2's. If that's you thing, then they might be just the ticket.
I lost interest in the M560's, partly because of what people said about them here; also because I now have planar headphones w/the perfect sound signature for my tastes (ZMF Ori). Still interested in the 1060 if/when it ever actually launches.