I've own both the TH-600 ad the Mad Dogs (albeit the rev3.0 which is now improved to 3.2).
In term of comfort, they both are top notch:
- The Mad Dogs have the best feeling of any phones (including the beyer dt-880) due to their excellent real lambskin leather pads and the perfect clamping force. They are a bit heavy (>400g) and end up weighting quite a bit on the neck in the long run.
- The TH-600 have a good feeling as well but the pads are stiffer, so you feel them a bit more on the jaws and cheeks. They are light and stay comfortable in the long run.
In term of sound, these are the antithesis of each other:
- The Mad Dogs are darkish with a forward (and
excellent)
midrange, linear and well defined bass and non-offensive treble. They provide the
best isolation (both inside & outside) of any phones I've heard (including HD-25).
They sometime sound congested with my setup (on the warm/smooth of things) and would probably benefit from a neutral/treble-forward setup.
- The TH-600 are V-shaped headphones with a very very nice monitor-like tonality (reminiscent of Focal studio monitors and XS Multimedia speakers). They simply sound open, at the expense of isolation (which is just passable when compared to the Mad Dogs). These have the
most refined treble I heard (I didn't hear the HE-6 yet but the 4s, 400s, 500s & 5LEs) and have a
very nice bass punch and definition (tight bass with good impact, not bloated). The midrange is quite recessed and would benefit from a mid-forward amp (e.g. tube amp like the Zana Deux or WA7 - I heard neither).
In term of price/performance, no doubt, the Mad Dogs are the real deal.
In term of pure performance, I preferred the TH-600 because:
- the tonality is more to my liking (Focal sound, again);
- my gears tend to be on the warmish/smooth to accommodate my treble-happy cans (AKG/Hifiman sound)
;
- they are lighter and more comfortable in the long run when sitting at my desk.
I just wish I had a tube amp to bring the mids back in the game...