Have directly compared with Ultrasone Signature Pro, Beyerdynamic T51P T5P and the KH (the on-ear version).
Sonically the KH has strong low-end (but not "mushy", as another tester was), a slightly recessed midrange and crisp highs. Just right for Rock, Jazz, New Age - a real fun handset. Even for classical music it is useful, although the KH can not keep up with the space illustration of Ultrasone.
Compared with the Beyerdynamic T5p the sound more balanced, stronger in the bass and absolutely was not tiring, which is T5P downright painful for my taste in the mids and highs - and I am over 50 and should therefore no longer even the heights so perceive as a 20 years. It's just important that you test the KH with the preferred music and the intended playback device.
The Sennheiser Momentum afforded a remarkable good result from - rich bass, treble, and good spatial reproduction - especially since it was by far the most affordable headset in this comparison. The T51P sounds much warmer in direct comparison, but the whole thing is really a matter of taste. From the outer appearance of the mountain is much more attractive than the more expensive by 80 T51P. The rivet connection between the headband and transducer mounting on T51P seems cheap, the positional adjustment of the earpieces is the T51P pretty stiff. By design, the T51P can not keep up with the Mountain, but the sound of her like it better than the Sennheiser me. For the Mountain has an integrated microphone and remote control combo with which one can control iPhone & Co and use to make phone calls, which none of the other KH offers. The Mountain is in my opinion the clear price-performance winner. The negative impressions of other testers I had not - headphone sound is something very subjective, and you should get an idea. Anyway, I found nothing to complain about at Senn.
I would recommend the Ultrasone music connoisseurs who listen to a lot of classical music, the momentum for budget-conscious connoisseurs, and the T51P for those warm, prefer deep bass.
