I have yet to hear complaints about the treble being turned up too much.. you're talking the XS? I heard the M80 back when I wasn't an audiophile and I remember being impressed. Comments like this make me wonder whether I should get the HD25s or XS.
Oops, sentence structure error on my part. The Mixrs had too much treble. The XS was more balanced, but sounded boring/off to me because of some weirdness in the 4kHzish region. I have a review of them going up on Headfonics in a couple weeks, but the general gist of it is: They sound good enough to recommend them over a number of other portable $200 headphones, like the Amperior (Great for its time, but they're rather harsh to my wimpy, warm-biased ears. Then again, they've been really easy to find around $110 which is ridiculous), B&W P3, and Momentum On Ear, but they definitely have their compromises to be so small. Just don't expect them to sound better than your HD558 and you'll be fine.