Sennheiser HD 518 3.5mm/ 6.3mm Connector Around-Ear Headphone

Pros: Great, clear, expansive sound. There IS a difference between even the best $40 headphones and these. They give you an extra 15% of your music, IMHO. Sure, they're the price of a dozen CDs, but all your music benefits.

The open vent design is great for work - the immersive sound effectively masks surrounding background conversations without being too loud, but doesn't drown out when someone comes into the cubicle to talk with me. I love this.

Cons: IMHO the vocals are maybe still a little under-represented, but they are on the low end of Sennheiser's good quality range. Headphone dot-com put them on their top 10 for phones under five hundred.
I was less impressed with the difference on my iPhone than on my laptop, say 10% better than other headphones. One tip - IOS6 - settings - Music - Eq -> off. (I had bass EQ enabled. It was one egg bad. I was going to return them).

Other Thoughts: These things are big. They sound big - the sound stage is more immersive and there is "room" to hear more elements. It's like the difference between a CD and live music - in a live performance many sonic elements are 'hidden'. These (and probably other good) headphones bring out subtle hidden elements to the music you've heard before.

Pros: Extremely comfortable for long listening session. Sound stage is incredible. The more I use them the better they sound. Very warm for such a good entry price in higher end cans.

Cons: None really, going to get a Fiio DAC/Amp combo to push it more.

Other Thoughts: The sound does bleed out more than I thought which can be a good or a bad thing depending if your spouse is sitting near you but that's something I knew in advance.

Pros: Awesome highs and mids, accurate and responsive lows. I love the open ended ear design, it lets my ears breathe and helps acoustically just like it's more expensive cousins, HD 555 and HD 598 offer. These are definitely audiophile headphones.

Cons: The 3.5mm/6.3mm adapter is way too large. Maybe a problem in certain situations

Other Thoughts: If you want noise cancelling qualities, do not get these. People can hear what you're listening to (and vice versa) if they sit nearby. However, this is the price you pay for the open ear design. They will beat noise cancelling headphones any day when it comes to sound quality.

Pros: High quality drivers, and a very well built construction based design. Clear Highs, and very enjoyable mids and lows. The soundstage is great. Detachable cable.

Cons: The headphones leak, but that is how they get their great soundstage. The hinges feel a little flimsy, but the headphones are very durable. The headphone comes with a built in 1/4 adapter, with a 3.5 mm adapter, but is quite large, and might not fit into phones or music players with a large case on, but not a huge problem, really.

Other Thoughts: These headphones are very good for their price. They perform great at reproducing highs, mids, and lows. I really think they are great headphones.

Pros: Great Sound and bass. Very comfortable

Cons: Very little outside noise cancellation. The connector 6.33mm + adapter is HUGE

Other Thoughts: Bought these to replace old Pro 280's The sound is better especially the bass. Only drawback is that it has less noise cancellation than the 280's so I had to turn up and use the volume control more now.

Pros: All around great pair of headphones and I've used them for about three months.
-The Sennheiser 518's are a great buy for the price.
-they fit comfortably on your ears for long hours of use.
-They have good highs, mids, and lows. They arent going to be the best headphones out there, but they are very good for the price.

Cons: The headphones original jack is a 6.3 mm and with the adapter the length of the jack can be annoying
-I had to shave off some of the rubber around the jack to make it fit in some of my speaker or PC plugins.

Pros: * Comfort: Deep cans. (My ears do not touch the inner speaker at all)
* Comfort: Circumaural; no pressure on ears.
* Comfort: Tight-fitting/snug.
* Appearance: Stylish?
* Sound: Very little distortion.
* Sound: Strong bass, clear mids.
* Sound: Can hear outside noise.
* Other: The cord is 10' long.

Cons: * Adapter: The 3.5mm adapter is rigid. (See #1 in Other thoughts)
* Appearance: Mild physical cracking may occur. (See #2 in Other thoughts)
* Sound: Can hear outside noise (Make sure you know this beforehand)
* Packaging: The headphone cord comes tightly wound, which can damage the sound quality over time.
* Other: The cord is 10' long. (Could be annoying/obtrusive, depends how you plan to use them)

Other Thoughts: #1: The 6.3 to 3.5 adapter sticks out far and is not well-constructed. If a mild amount of pressure is applied to the plug while it's in a port, the port or plug may be damaged. Thus, I've purchased a Grado adapter for its flexibility.

#2: My closest comparison is the Sennheiser HD555s, which I have owned for almost two years. The 555s demonstrated mild physical cracking near where the head pad slides out (i.e. the highest point of silver when you're wearing them). These 518s appear to have the same design.

The box was well-packaged with peanuts.