1. Koss Pro DJ100 / TBSE
Sounds better than my HD-650 with the same setup if you ignore the fact that the HD-650 is open (which is a slightly unfair advantage). As much as I love my HD-650, it doesn't really sound technically better in any way. Yeah I know about all those wonderful measurements. What holds the DJ100 driver back is it's enclosure. Koss could do so much more with this one. This one seemed to benefit more from equipment upgrades than my HD-650. About the same as my Q701. This thing is so revealing of every single change in your setup. Feel free to call me nuts if you want! Like the K701, it's easy to hate this with the wrong setup. It's best with very neutral gear to my ears. I want to see an open HD-650 killer from Koss
2. AKG Q701
No clue why I put the HD-650 above this last time. This thing got even better when I did some upgrades recently. I think it pretty much couldn't possibly sound any better, but it did. This headphone with my setup is not too forgiving anymore of poor recordings, but yet is still not fatiguing at all ever. It's treble is really smooth.
As much as I hate to say it, but the DJ100 sounds often more detailed and clearer. It's sometimes easy to get confused because the DJ100 is warmer/bassier. When my DJ100 sounds less clear than my Q701, it's the fact that the recording is what's not clear! No joke. I didn't realize stuff like this until I tried gaming.with my KRKs and the soundtracks were more muffled on very revealing CLOSED headphones.
3. Sennheiser HD-650
I love this headphone. It's not boring, but is slightly laid back at times. I didn't think so at first until I compared it to my other headphones. It's nice and full sounding and very well balanced. Mine is even more balanced sounding in the bass than my HD-580 and 600! Makes no sense right? It doesn't seem dark to my ears. It has slightly less treble than my HD-650. No huge mid-bass hump on this pair.
Despite sounding very smooth it's almost too forgiving and makes nearly everything sound almost too good.
I tend to hate this with warm sounding sources. It was awful when I tried it with the Clip+ to amp (not that I'd use that setup).
None of my other headphones have gotten any use in a long time. It's safe to say that these are not going anywhere and will be use for many years.