Pros: Balanced sound on the cheap
Cons: Resonance in metal parts - Comfort (gets better with time)
Comfort:- Been said before - strong clamping force. The pads are large but I wish there was a little more room inside for my largish ears. Out of the box not real comfortable but wearable. After having them for a week they have improved some and I believe will continue to improve as they get worn in. I can wear them for hours so they must not be that bad!
The sound is impressive though. Using exponential tone sweeps and sinegen they aren't perfect for me but they are much more balanced after 2k than my hd595's with fewer and less extreme dips and peaks, and the low end is no competition. They have the typical headphone scoop in the 4k region with a pretty good jump around 5k. The mids and low end stays even and strong until around 30. Over all I really like them and find them very balanced. Nice balance between kick and bass guitar. I don't hear any strange low or mid resonance like I did with the the rp-htf600. I usually mod everything I get but I just might leave these as they are. Wow. I can't believe I just typed that...Actually I did do one little mod. The metal clamping mechanism has a very annoying resonance so I put a chunk of closed cell foam between them as shown. Looks goofy but problem solved.
After analyzing these more I don't think they are a Superlux hd662f but are closer to a standard hd662. I base this on what I am hearing compared to the Superlux frequency graphs. The hd662f has a low end roll off where as the hd662 does the opposite and that is what I am hearing below 100hz - a bit of a rise in response to about 40hz were they then begin to drop. The upper frequencies also match the hd662 graph with a rise at around 4.8k ( after the 4k dip) slight dip at 5k and another peak at around 6k etc..
I am not sure but they may not be much at revealing bad mastering compression. Or maybe I should say they may be good at making everything sound pretty good. Elvis Costello's A man out of time, which is horribly compressed sounds better than it should. I can hear it pumping and breathing all over the place with the Sennheisers.
I used the mh310 to remix some old tracks using Reaper ( a fantastic program! ) an emu 1212m and a cmoy variant. These cans got me very close which I have never been able to do with headphones. The kick is actually balanced in the mix. With a little more work I think that these would actually make mixing with headphones doable. Not ideal of course but doable.
In conclusion, from the perspective of frequency balance these are the one of the best headphones I have heard. Period. Now I don't own nor have heard many high end headphones. I have owned or own Sennheiser hd595, panasonic rp-htf600, and sony mdr-somethings (don't remember). I have tried to mix with akg240's. I have briefly tested the krk8400. For frequency balance these beat them all (except probably the krk) and are highly recommended. Do they have the comfort, soundstage or low distortion of the 595? Of course not but they are so much more balanced that I will rarely use the Senns. I suspect to substantially better them I would have to spend at least $100 more.