Pros: Light weight, comfortable, soundstage, nice highs, replaceable cable and ear pads, visual design.
Cons: not portable or public (open back) average sub bass impact.
I bought these back in 2000 for full retail, which was a lot of money for me at the time. I got to A/B these at a hi-fi shop using my reference CD. I listened to the HD600 and the HD590. I really enjoyed the sub bass impact on the HD590. I was buying them as reference /monitoring headphones for making music with a lot of sub bass content. (It's not always cool with my neighbors to blast sub woofers) They don't have a particularly flat FR, but that is not what I was looking for. I was looking for something that could recreate or replicate my 4.1 desk system that is based on car audio which is what I make music for in the first place. (the cars that go "BOOM")
The Sennheiser HD590 has served me well for over a decade. They are not fatiguing, and work well for long work sessions. They remain cool and comfortable, which allows me to continue working. Most importantly, I can hear my wife when she pokes her head in the door and says some completely random non sequitur that requires a considerate response or my work will be cut short ;-) So, Sennheiser has improved my quality of life. (Thank you, Senn)
I am writing this review because in doing research for new headphones, I found that these HD590s only had two reviews. I believe that these deserve more attention than that. Also, it is rare that I can add something to Head-fi that has not already been said better.
(Thank you Head-Fi for taking me from Walkmans to Tube Amps)
In short, if these were the only headphones in my life, it has been a beautiful ride.