I've owned the HD595, DR150 and HD600.
I and have used Cute Encore+Spitfire and currently the 0404USB as my source+amp.
( I'm only a poor guy that likes music a lot and have to save money for other interests -> not a really crazy head-fier )
HD595 :sound-9.2 , comfort-9.8, build-8
DR150 :sound-9 , comfort-8.5, build-7
HD600 :sound-9.5 , comfort-9.5, build-9.5
Although I prefer the balanced sound of the Sennheiser phones, the DR150 has REALLY good, never bloating and well-controlled Bass that I enjoy alot.
The only thing to complain about the Docs ( for their price ) is the build quality.
After 1.5 years of every day use (for I use it A LOT) , the weak plastic part on the adjustable headband begin to show cracks and is expected to be totally broken for within another 1.5 year...
The DR150 is quite small, and if you have a bigger head as I am, I guess you may have the same problem one day...
Rough estimations (guesses) for the life expectancy of the 3 headphones based on the build quality :
DR150 : 3 years -- broken headband at the size adjustment portion
HD595 : 3~4 years -- broken headband at the swivel connector
hD600 : 8~10 years+ ... -- I cannot imagine this headphone is going to break down, possibly the
connectors for wires on both ends... but I heard it's fixable.