After quite a long time of lurking and simply using these forums to read up on stuff I'd like to buy, I've decided to become active myself.
I currently own a pair of Sennheiser HD 558's, Shure SRH1440's, Sony MDR-1R and tomorrow I should be getting a pair of HD 650's in the mail. I've been listening to these on my stereo receiver (the MDR-1R's on my iPhone/iPod), which, after buying the Shures, will be replaced by something decent soon.
Now the problem is that I really really dig the sound of open headphones. So much, that I haven't been able to enjoy closed headphones (the MDR-1R's are decent, but I really only ever use them when on the road). Open headphones just aren't of any use if there's any kind of noise around, so I'd love to have closed headphones for those moment. So what kind of headphones would be suitable replacements for their open brothers. The open sound I like speaks for itself, the music I listen to is a lot of instrumental (classical, (post)rock, etc.) and music with mainly vocals. I really enjoy the airy and analytical sound of the Shures, although I also took a liking to the more fun sound of the Sennheisers.
The second question is about DAC's. I've read quite a lot about amps and the way they influence sound, do DAC's do the same kind of thing? Which means I'd have to think about three components when buying components.
Thanks a lot for helping me out and please correct me on any use of plural words (in Dutch, headphones isn't plural, for example).