When I sit down to test out a pair of headphones, I'll usually do some A-B testing between a couple different pairs of headphones to make sure I'm hearing what I think I'm hearing. With the HD559 open-back, over-ear headphoness from Sennheiser, though, I knew immediately that something was off, even before I sat down to compare. They're not bad per se, but I'm confused about who Sennheiser thinks they're aiming these headphones at.

What's in the Box

The physical headphones themselves are where the questions start. The headphones aren't bad looking, but they don't look expensive or premium to me. They look strictly middle-of-the-road, which fits the $99.99 pricetag you can find these for in most places. They're not particularly stylish, but they're not ugly, either.

It's the cord that gets me.

While the headphones look middle of the road, the detachable cord suggests that Sennheiser either isn't paying attention or thinks audiophiles might like these. The detachable cord itself is going to be appreciated by anyone who beats up their headphones or has pets that aren't always the nicest, and at almost 10 feet long, you have plenty of slack to walk around with. But the HD559s only come with one cord, and that cord terminates in a 1/4-inch jack at the source end. I was so convinced this had to be wrong that I took apart the whole box looking for the 3.5-mm jack that most people will be using.

I own 3 sets of headphones right now, and I've owned many more over the years. But despite owning headphones from Sony, Shure, AKG, Audio Technica and more, I haven't come across a pair of headphones that not only makes the 1/4-inch plug the default option, but also the only option. It's baffling to say the least. I have countless pieces of hardware in my house that take a 3.5mm jack but nothing that will accept a 1/4-inch one. I mentioned this to a friend (also a tech-savvy audio fan) and he said "what, like on an amp?"

The only places I can recall seeing 1/4-inch jacks are on amps, musical instruments, and stereo receivers. In other words, not the places most people are mostly listening to music these days. So I had to dig out my 1/4-inch to 3.5-mm adapter to test these out, and everything I listened to filtered through that. If you're the type who feels that can recognizably change the quality of the music you're listening to, then you'll want to keep that in mind when we get to sound quality.

Aside from that, the box is all but empty. Paperwork is the only other thing you'll find in there. No second cord for that 3.5-mm jack, no alternate ear cups, or anything like that. It's a simple presentation, but not a bad kind of simple if you can get past the whole jack thing.

Getting comfortable

Of course, they have to fit on my head and feel good if we're going to listen to them for a long time, right? The 559s are about average in this respect. The foam earcups are comfortable, but overly firm for my tastes. There's plenty of room inside for bigger ears, unlike with the Audio Technica ATH-M50x headphones, which push on my ears if I don't get them just right. The top headband is softer than the ear cups though, and that helps ensure they stay on firmly even as I vigorously move my head around like a character from a Tool video.

How do they sound?

The 1/4-inch plug would make sense if these headphones sounded great and were meant to appeal to the kind of audience that has 1/4-inch jacks all around them, but I wouldn't let these within a thousand feet of a recording studio, and an audiophile would excommunicate you for bringing these into their home. Audiophiles are weird.

The simplest way I can describe the sound of the HD559s is like listening to music wearing a foam helmet. Let's dive into what I mean by that.

First is the sound stage. When I listen to a song like "Sweet Charity" by Mr. Bungle, I'm used to hearing a wide sound stage that conveys the weird, ethereal feeling of their music. On the HD559s, it felt as if we'd all been packed into a small room together. The same went for the sound on any track on Miles Davis' "Kind of Blue," one of my go-to albums for listening to new headphones.

Diving into the particulars, I would say that the HD559s over-deliver on bass. That sting about 18 seconds into Led Zeppelin's "Immigrant Song" is a feast for the ears on a more balanced set of headphones, but here the individual elements blend together into a single sort of noise that puts bass at the front and the other sounds toward the back. Mids and even highs can get muddled behind the overly-heavy bass.

It's worth noting that if you listen to mostly vocal-forward music like a lot of hip-hop and rap you might get a lot out of the HD559s. In a track where vocals are at the front, backed by a beat or some orchestration, these headphones are actually pretty good. Vocals are clean and clear in songs like Atmosphere's "Guarantees, Aesop Rock's "None Shall Pass," or Wu-Tang Clan's "C.R.E.A.M." sound good. Kesha's "Blow" works well on the HD559s as well.

The HD559s are also loud. My AKG K240 MKIIs are much more even about delivering the actual music, but the HD559s are significantly louder plugged into the same device at the same volume. These are open-back headphones, though, so keep that in mind if you're wearing these outside the house. Everyone is going to know that you have Let It Go and Rain of Blood on the same playlist.

At $99.99, the HD559s aren't way overpriced – they're going to outperform a lot of headphones out there that put you in the same price range but focus more on packaging and marketing. But I won't be running out to buy myself a pair to replace my K240s as my open-back headphones of choice anytime soon. The confusing package of a 1/4-inch plug and sub-par sound tell a story of a product without an audience, and there are much better shows in town.

Thank you to Audio46.com for supplying the headphones for this review.

Check out the HD559 or other Sennheiser and audiophile headphones from Audio46.com.

2.5 out of 5