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The Massdrop x Sennheiser HD 6XX Sold Me on Open-Back Headphones

Rating: 9/10 ?
  • 1 - Absolute Hot Garbage
  • 2 - Sorta Lukewarm Garbage
  • 3 - Strongly Flawed Design
  • 4 - Some Pros, Lots Of Cons
  • 5 - Acceptably Imperfect
  • 6 - Good Enough to Buy On Sale
  • 7 - Great, But Not Best-In-Class
  • 8 - Fantastic, with Some Footnotes
  • 9 - Shut Up And Take My Money
  • 10 - Absolute Design Nirvana
Price: $220
The Massdrop x Sennheiser HD 6XX plugged into a phone.
Michael Crider / Review Geek

Open-back headphones are a product still firmly planted in the audiophile niche. But if you’re looking to see what all the fuss is about with a set from a reliable brand that won’t break the bank, then Sennheiser’s HD 6XX is a perfect place to start.

Technically these headphones are a collaboration between Sennheiser and Drop (AKA Massdrop), which has a sizable catalog of audiophile offerings. A somewhat customized version of the HD 650, the HD 6XX rings up at $220, with optional upgrades for things like VELOUR EARCUPS. If you’re expecting frills, you’ll be disappointed: this is a wired set without extras like a single-side cord or travel-friendly rotating earcups.

But that’s okay, because the HD 6XX isn’t designed to replace conventional headphones. It’s a way to explore your high-quality music and movies in extra fidelity, without spending a ton of money or using a ton of space that a huge array of speakers would. And in that very specific capacity, it delivers.

What’s Different About Open Back?

If this is your first time seeing an open-back or “backless” headphone design, check out this guide on How-To Geek. And if you want to ignore my suggestion and make me feel bad, I’ll explain it here: whereas the exterior housing of the earcups on conventional headphones are solid plastic or metal, open-back headphones use a grille or slot design that exposes the back of the driver and other components to the air.

The open back casing on the HD 6XX headphones
See how you can see the inside of the headphones? That’s the “open-back” part. Michael Crider / Review Geek

Why? It creates a more open, balanced sound experience. Whereas conventional headphones are all about isolation, closing you in with your music, open-back designs allow for a more natural sound profile, as if you’re listening to performers in a “real” space rather than inside your head. The difference is almost impossible to get across in text; the best way I can describe it is that they sound less like headphones and more like speakers that just happen to be sitting on the sides of your head.

There’s a downside to this sound profile: noise, both internal and external. Open-back headphones allow in more ambient noise from the environment, with almost zero noise cancellation effects. For example, even at a high volume, I can still hear my keyboard through the music in the headphones as I’m typing this. Open back headphones also allow much more noise out into the environment; if you’re listening to a podcast, someone else in a small room would probably be able to quote the host word-for-word.

the HD 6XX on a much better-looking man than me.

For both of these reasons, open back headphones are unsuitable for environments where you want to keep the music to yourself. Don’t bring them to a library, an airplane, or a Starbucks. Unless you’re a jerk, I guess. Then feel free to sing along while you gargle your Frappuccino.

Amazingly Natural Sound

Not being a “true audiophile” myself, the HD 6XX is my introduction to open-back headphones. But even given the limited utility of headphones that don’t travel well (and aren’t intended to do so), I have to say that the experience is pretty fantastic. On paper, the set’s 10Hz-40kHz range is amazing—almost certainly better than your natural hearing ability. In use, the sound is more dynamic than any set I’ve ever used before, with clearer mids and highs, and better differentiation of specific voices and instruments. The illusion of “space” instead of isolation is unlike anything else I’ve ever used.

The exposed drivers of the HD 6XX
Note that you can see the mesh exterior casing right through the driver. Michael Crider / Review Geek

The set won’t blow you away with pure volume without a dedicated amp, and the open nature of the cups means that it doesn’t preserve head-thumping bass like a conventional headphone design. If you like to rattle your fillings when the bass drops, these aren’t the headphones for you. And as previously discussed, noise cancellation and sound isolation are almost zero.

But in terms of actual sound quality, it’s a revelation. I’ve found myself listening to the HD 6XX at my desk, preferring it over my (very good) Edifier R1280T bookshelf set for extended work and play sessions. Again, this is hard to put into words you’ll understand unless you’ve tried something similar. The best I can do is this: standard headphones sound like you’re listening to a recording; the Sennheiser HD 6XX makes the same music sound like you’re listening to a performance.

Like Wearing a Jeep on Your Head

I was surprised at the somewhat old-fashioned design of the HD 6XX, almost entirely carried over from the HD 650. The design lacks many of the elements you’d expect from “modern” headphones, like a single-sided cable, in-line mic, folding band, or rotating cups. This stuff isn’t a deal-breaker since these headphones are very much not intended to travel. But their absence is notable, like roll-down windows on a 2019 Jeep Wrangler.

The HD 6XX In its storage case.
The HD 6XX comes with a huge and impressive storage case. Michael Crider / Review Geek

In fact, that Jeep is a nice simile for the HD 6XX, since it’s also technically a convertible. The metal grille cups on the HD 6XX effectively show off both its central technical feature and its most striking styling decision. But with the back of the internal driver exposed to air and dust, you’ll need to baby it a little: it needs to go back into its case when not in use. I was initially put off by the lack of a carrying case, until I realized that the absolutely massive foam-lined presentation box (which would make this set a good one for gifting, incidentally) works as a perfect storage box, too.

Our review unit came with velour pads, soft and with a good seal. I was surprised to find that they didn’t leave me hot and sweaty; I’d say the extra motion of air via the open back is keeping my ears from getting as toasty as they usually do. Velour and sheepskin are upgrade options. The band pad has a split design that feels great on my (admittedly pointy) head, but those who don’t like a tight fit might not appreciate the stiff tension and relative lack of adjustment options.

The headphone cable of the HD 6XX.
The cable is 1/8″ with an included adapter, and can be easily removed from both cups. Michael Crider / Review Geek

Styling is surprisingly simple: aside from HD 6XX badges above either cup, a Massdrop tag on the inside of one side and a production number on the other, there’s only a super-subtle black Sennheiser logo on the  dark blue band. Inside that enormous presentation box is an ⅛”-to-¼” adapter for those of you with older or high-end audio equipment and…nothing else. The proprietary cable can come out of both sides for easier storage.


$220 is a lot for most people to spend on headphones. But when you consider that the Massdrop-branded HD 6XX has identical hardware specs to the Sennheiser HD 650, which has a retail price of $500 and usually goes for around $320-350 street price, it’s a steal.

It’s worth noting that Massdrop says these headphones can be disassembled and repaired by the user, presumably using Sennheiser’s HD 650 parts, which are easy to find online. (I gave this a try after a quick YouTube search: it doesn’t even need any tools!) If you want these to last, and you don’t mind a little basic maintenance, they should be easy to get up and running again if you break them out of warranty. That’ll make our friends at iFixIt very happy.

The HD 6XX completely disassembled.
I took the whole set apart without any tools. Michael Crider / Review Geek

A similar Massdrop collaboration with Sennheiser, the HD 58X, costs $160, but has a tighter frequency range and similar compromises in other audiophile specs. It might be a better choice if you’re on a budget.

A Great Way to Mix It Up

Considering the price, the sound, and the capability, the HD 6XX is an amazing set of headphones. Don’t buy it for travel, or wireless, or noise cancellation. It’s not good at any of that, and it’s not intended to be.

The Massdop logo is on the inside of the band.
Michael Crider / Review Geek

But if you’d like to see what the fuss is about open-back headphones and you want a great deal from a well-known name, the HD 6XX is a great buy. Unlike most of Drop’s group buy offerings, it’s available to purchase and ships immediately but might go out of stock for extended periods as new units are manufactured.

Rating: 9/10
Price: $220

Here’s What We Like

  • Amazing sound profile
  • Competitive Price
  • Good storage case
  • Tool-free disassembly

And What We Don't

  • Bulky
  • No single-side cable

Michael Crider Michael Crider
Michael Crider has been writing about computers, phones, video games, and general nerdy things on the internet for ten years. He’s never happier than when he’s tinkering with his home-built desktop or soldering a new keyboard. Read Full Bio »