Sound:
I tested out the Sennheiser’s HD 558 as well as the HD 598. These 2 headphones are VERY similar to each other. However the 598 seems to slightly have more of a punch/base to it and a very slightly wider soundstage, while the 558’s are a bit calmer with fewer base, exactly what I was looking for. The 558’s are a very good headphone, even un-amped, these headphones are so easy to power, however I do recommend getting an amp to get the most out of these headphones. The sound on these are very crisp and clear, puts all of the $10-$150 headphones/ear buds I’ve used to shame. There isn’t a whole lot of base, but it does make a very slight presence, but I’m sure the right amp can change all that too. Soundstage on these headphones is very nice too. Overall best sounding headphones I’ve ever used. I should note that these sound good with lower quality mp3 (192kbps + lower), but I do recommend using these with higher quality audio (320+kbps).

Comfort:
The 598’s did feel a bit more comfortable, felt silkier which was very nice, but the 558s are still very comfortable, almost the same as the 598s, and they also seemed more solid/sturdy than the 598s as well. Im wondering if I’ll be able to buy the pads for the 598s and switch it with the 558s, the colours wont go together but I dont care, since these will only be used for home. Since these are open, these feel very good. My ears didn’t get warm, and I felt like they can finally breath, coming from someone who’s used closed cans. I can wear these headphones for hours on end with no problem, my ears don’t even feel “plugged” after wearing these.

Design:
These are open headphones, so yes, you can definitely hear people talking, not as bad as I thought they would be but it didnt feel as if I wasnt wearing any headphones, there was some slight ambient noise blocking, however I would only use these in a quiet place, I only use these at home anyways to watch movies/games at night and they are perfect. These headphones are pretty sturdy too, though I have to admit I’ve taken very good care of them, but I felt like I’ll be able to drop them a few times without any problems.

Pros:
Clear, crisp, detailed sound.
Very Comfortable
Sturdy, well designed.
Excellent sounstage.
Less base.

Cons:
Senns Hd 598's pad felt nicer.
While sounds good unamped, these should be hooked up to one.
A bit forgiving with lower quality audio, however at 192+ kbps mp3's are recommended.


I’ve also tested out the Senns HD 800, supposedly the world’s best headphones, there wasnt a dramatic difference in terms of comfort, but it did fell a lot more airy, lighter. To be honest, these headphones werent really amazing as everyone says they are. The 598's were just as good as a headphone, The 800 seemed to have a lot of that in your face sound, but thats just me, however they sound very crisp and clear, soundstage wasn’t as big as people say they were though. These headphones are hard to power up, and it was only hooked up to a small external desktop amp. Really good headphones, but definitely not worth the huge price tag at all.

Conclusion:
Overall Im very happy with the 558s. These will work just fine with any mp3 player un-amped, but I do recommend getting an amp, it just takes it to another level of sound. Mostly because of the price I had gone with the 558, however I still didnt feel like there was a huge difference between the 558 and the 598 if at any. If you want a headphone that isn’t too expensive, has a nice soundstage, and very crisp, clear, and detailed sound, and will be using these at home for movies and games, then these are the perfect fit for you.