Sennheiser Massdrop HD 6XX Headphones Synopsis – The Renowned Open-Back

Sennheiser HD 6XX Headphones

This Synopsis

Sennheiser’s collaboration with Massdrop (now just called “Drop“) to push the bang-for-the-buck envelop for striving audiophiles has turned out quite the success. If you’ve kept up with the best values in over-ears, you’ve likely heard of Sennheiser’s/Massdrop’s repackaged open-back HD 650‘s in the form of the HD 6XX. Its slight cut back on materials but none on sound quality approach has been met with a lot of praise and word-of-mouth recommendation, so much that we had to test it out ourselves.

There are plentiful reviews out there and overviews of the HD 6XX’s design and function. Rather than rehash all that, this synopsis is meant to aid after the general “review”, compiling important points and criticisms that often go unaddressed. Let’s get right to it….

The Rundown

Sennheiser HD 6XX Headphones
No-frills packaging – Headphones and detachable, unbalanced 3.5mm cable with proprietary 2-pin connector.

Sennheiser HD 6XX Headphones
The detachable cable unfortunately utilizes proprietary 2-pin design, which limits third-party choices.

> It is as expected that $200 audiophile-grade headphone will have average build materials. The headphone is mostly a hard plastic affair (save for the grills on the outside surface of the ear cups and the inner band that is exposed upon expanding the headband size) but is put together solidly. There’s no lack of confidence in it lasting.

> Likewise, the ear cup and headband padding don’t have any fancy, eye-catching leather-like coverings and are just fabric. However, they’re mindfully implemented when it comes to function. The cushioning isn’t too soft or firm, and has a bouncy and breathable quality. It feels like a cloud on the head and isn’t fatiguing (probably also due to a great combination between ideal clamp force and light weight of the unit).Sennheiser HD 6XX Headphones

> The HD 6XX are ergonomically a joy. The weight, padding, and clamp force are all so right. The ear cups have perfectly sized openings to completely cover the ears with minimal contact and seal around them.

> With an impedance of 300 ohms, you likely won’t be running these out of a smartphone (unless it’s one of the select few with a dedicated DAC/amp inside, like LG’s flagship phones). If you are adamant on it, you can grab a small amp to put between the phone and headphone.

Sennheiser HD 6XX Headphones
Ample head padding and center cut-out to try alleviate the annoying top-of-the-head fatigue.

Sennheiser HD 6XX Headphones
The ear cups’ adequate size, shape and rotation means you’ll likely get a snug and comfortable fit.

> This headphone will attract a lot of newcomer audiophiles, but that may not be aware of sound leak of open-back designs. Open-backs are capable of the best soundscape but at the cost of isolation. You will hear everything and everything will hear you. This kind of headphone is meant to use at home where you can’t disturb others and vice versa.

> First addressing the open-back quality. We must say that we were a bit underwhelmed by the soundstage. Coming exclusively from closed-back headphones, we were expecting the switch to an open-back over-ear to awe. Well, that’s not going to happen with the HD 6XX. It’s a big, encompassing, 3D sound no-less, just not a particularly wide one.

Sennheiser HD 6XX Headphones
The acoustic design and output of the HD 6XX is exactly the same as the pricier HD 650.

> Openness and airiness are uniformly above average, so you do get something for the open-back nature. But a well-done closed-back headphone can achieve this (granted at a significantly higher cost), which would isolate sound too. With the HD 6XX, one must recognize the compromise for the aggressive price.

> Likewise, clarity isn’t particularly stellar. Again, alternatives up the price chain will clear the view up. The biggest culprit of muddle is the range from mid-bass to mids. Thankfully, Sennheiser didn’t push the mid-bass too much; it’s borderline bloated. But as it stands, it should be a nice balance between impact and quality for most people.

> We don’t know if it’s the strong mid-bass but the frequency response sounds U-shaped to our ears, for better or worse (that’s up to the listener really). In other words, it’s a slight recess in the mids. Fortunately, due to the open nature of the headphones, it’s of little consequence. Elements in this range like vocals and guitar strums don’t sound dull or confined, just not as pleasingly forward as more balanced spectra (again, usually which comes at a higher cost).

Sennheiser HD 6XX Headphones
Our dedicated DAC Mojo (Mojo+Poly shown here) has plentiful power for the HD 6XX and gives the bass and mid-range some nice body.

> Dynamics are well done. Despite not having a wide soundstage, the placement of the sounds is pretty clear to the listener. You get nicely surrounded by everything and it’s easy to get lost in the music. This is a quality that showed as a clear benefit from in-ear headphones, for instance, which have a hard to simulating a sound this big and encompassing.

> One of the things we appreciate most is that nothing is notably laid-back – a big reason on why we believe these headphones are so popular. Whether bass, mids, or treble, the details are present and easily audible. Although, it’s short of crystal clear like in more expensive options. Another thing is that the upper treble won’t necessarily reach those sparkly highs, nor will sub-bass reach attention-grabbing depth. Again, have to remember that the HD 6XX is a great all-rounder, but not superb at a particular thing.

The Summary

Sennheiser HD 6XX Headphones


  • Awesome performance for value ratio
  • Terrific fit and comfort
  • Detachable cable
  • That “open” and “airy” sound from an open-back


  • Mediocre plastic feel and arguably ho-hum look
  • Proprietary cable connector limits third-party use
  • High impedance means may need extra amp to drive
  • Soundstage for an open-back leaves to be desired

Official page for HD 6XX on

We’d say that the HD 6XX’s popularity is fairly well justified. It can’t be denied that you’re getting a lot of headphone performance for the $200 asking price. And this is with something that’s not compromised ergonomically. Materials sure leave to be desired, but as long as the build works and isn’t flimsy, we can’t see this as a significant factor.

That said, it’s not reasonable to expect that you’re getting a top-end or even near top-end solution when it comes to audio quality. Many good, higher costing open-back cans have a distinct advantage with soundstage width, clarity, and extension details, especially when you get into the various choices with planar magnetic drivers. But the HD 6XX is a fantastic entry level into that world.

Also See: Beyerdynamic DT 770 Pro Headphones Synopsis

Josh is so enthused about tech that he writes about it. After time at several tech publications, he launched The Synops - concise and quality gadget synopses with information that readers want to know and details they want to see. You can also follow him at on Twitter (@joshnor713) and Google+ (+JoshNoriega). Email any inquiries to

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