Well I recieved my GR07 MK2 (Black) yesterday and have bene listening to them and also done some brief comparison with MK2 Classic (Red).
Before I give impressions I have to state that the MK2 I recieved was not in a sealed box, and I have a feeling they have been used before (I am in contact with eBay seller deng8718 about this). Therefore I do not know how they sound fresh out of the box, on the flip side I guess some burn in has already taken place for me lol.
I can tell you one thing right off the bat, they sound completely different, the mids are much clearer and prominent on the MK2, which is something I felt lacking on the Classic when I compared them with RE-400 previously. The overall sig I would say is flat and warm.
-GR07 Classic - V-Shaped sig, good bass, mids slightly recessed (veiled), harsh treble at times (but getting better with use)
-GR07 MK2 - Flat but warm, deep punchy bass, mids are neutral and clear, treble is well extended with little to no harshness (don't know about burn-in effect)
-RE-400 - Flat and very slightly warm, least bass but well defined/punchy, super mids, nice treble (burn-in has opened up the soundstage and better bass impact)
So from this I feel that the driver being used in the Classic is different, as to my ears it has a completely different signature compared to the MK2. The classic is not bad sounding at all, in fact I think it compares quite well with IE80, but with a different kind of treble, the treble on the IE80 was quite excellent but was always overpowered by the bass.
Can any MK2 owners please let me know if the sound I have described matches their experience, would be good to know.