Just to keep this thread live
I have few Denon headphones: D600, HP600, HP800, HP1100, MM400 and D7200 on the way.
The difference between D600 and HP700 / HP800 is pretty significant. The HP800 sounds better, have more detailed & clear sound plus more punch in bass. The only area where D600 is comfort and soundstage. The D600 are very comfortable headphone but I have smaller head and it does not seal properly my ears. When I use my fingers and make the D600 more tight the sound improvement is significant (still not better than HP800). The HP800 at the moment are the best sounding headphones I own and I have tried plenty.
The D600 also have very very soft pads.. they will torn by itself after some time. I have replaced them with a bit thicker and deeper pads and they work very well.
For HP800 I purchased pretty deep and very soft new pads from China and they are amazing. The sound quality improved in terms of better bass, added soundstage, added comfort and slightly softer highs. They are my top cans for now. If you have them do not take them out make sure you take care of them. They are the most underrated headphones I know. They are nowhere to be found now as the production finished
I wanted to purchase one more units for myself and some more for my friends.
The Denon headphones have this great signature sound I cannot get enough of.
The HP600 sound pretty close to HP800 but no soundstage and they are very small. On the other side the seal is great and they are definitely a good option for travelling and mobile djs. They are way better than HP1100. The HP1100 is the biggest disappointment... the sound is ok but nowhere close to HP800 / HP600 little closer to D600. The bass is great but thats all. The highs and mids are not clear enough plus they are very heavy headphones and the extensions on cups are made from PLASTIC where HP800 has metal reinforcement there same as the HP600. I believe the HP600 / HP800 where done by some quality production team where the HP1100 coming form somewhere else. The HP1100 have 53mm driver and they are not dynamic enough comparing to HP600 / HP800. They are not in this league at all but still I decided to keep them.
The MM400 are great headphones... pretty close to HP800 but somehow its not enough. There is something unique about the HP800 they just sound more lively and the bass is better. The MM400 with thicker pads got improved sound and mainly in the bass region. They are marketed as portable headphones but please do not take these out. They can scratch easily and they have wooden cups so cannot imagine if they get wet. They are still excellent headphones for all type of music, movies and even games. I do recommend to change the pads and mainly the cable which is really bad quality out of the box.
My current list in terms of sound quality:
1. HP800
2. MM400
3. HP600
4. D600
5. HP1100
All these headphones are worth buying and some of them you can get with a great sale price and some of them became a rare ones you wont be able to buy easily (HP600 & HP800). Do not buy HP1100 they are not good enough and very heavy.
Soon I will compare all these to the D7200. I would be also interested to purchase the D7000 to extend my collection.