Summary: Clear, well-defined and balanced sound; loud enough; comfortable; affords quite relaxed listening not punchy, or harsh in any way. Worth the few extra dollars? Definitely. I recommend these headphones.
Summary: The Sennheiser HD555 headphones are an excellent value for its modest price tag. It delivers nice, tight (though not particularly loud or impactful) bass, nice liquid mids and detailed though ever-so-slightly grainy highs. The velour pads don't heat up my ears as much as the pleather pads on some other headphones, and aside from the slight contact of the driver plane on my ears, the HD555 is comfortable to wear.
Summary: The sound of those headphones is pleasantly deep. That kind of deepness one couldn't get on the portable earphones. Therefore, those headphones are great for the movies, soundtracks, and games. How about comfort, it was almost perfect. However, due to the fact, that those headphones were open and didn't isolate any sound, I decided to replace them with Sennheiser 265 HD linear.
Summary: The pads are really soft and seem to be durable. Sound quality is really good. specially with mids. Pros: Durable, flexes well. soft pads, doesn't fall of head in any way. Sound quality is 7/10. Cons: My left ears keeps hurting for after 4h of wear.. I can lower the pain by moving it but i can't get rid of it. I had the same problem with Philips SHP805 but then it was really bad.
Summary: These are excellent entry level headphones. Build quality is a bit flimsy, but comfort is very good. Very easy to drive, but bass was quite bloated unamped and needed amp to tighten it up. The extension is excellent, they go deep. Make no mistake about it, these are smooth laidback cans, not the most detailed. They won't have the punch you're looking for if you're a basshead. They are also too 'slow' for rock. They do jazz, acoustic, classical well, but excel at vocals.
Summary: The HD 555 are great value headphones and are 90% of the HD 595 for a lot less money. They are basically a slightly less refined headphone to the HD 595. The velour pads are very comfortable. These headphones are easy to drive and have a relatively neutral sound signature, leaning towards warm.
Summary: These are a pleasure to listen to. A fairly intimate feel that shines on classical, light rock, jazz, and vocal tracks. Great for movies as well, with a great soundstage. It's also one of those headphones that you forget you have on. Lightweight and very comfortable, the earcups seem to magically conform around your ear. Fairly well improved with amplification, but not as drastic as the ratings seem to point (I rated 5).