Apr 24, 2012

Sennheiser MM 550-X - Box Contents, Features And Modes, Opinions, Battery Tests, And Images

Gear: Sennheiser MM 550-X, Creative Audio BT-D1, Sennheiser BA 370 PX, Bose AE2.

For the longest time I have seen some epic Sennheiser headphones, usually found positive reviews, but I never tested them. The Sennheiser MM 550-X did caught my interest with the Apt-X technology.

Usually Bluetooth audio loses a lot of quality, and when I heard of Apt-X bringing audio quality up to CD level I thought they were "bsing" the world. So I dug in $500 of the earnings of the blog and bought the MM 550-X headphones for testing. Of course I also had to spend $40 getting a Creative Bluetooth BT-D1 to get the Apt-X working.

I do not want to create one lame giant review post/video. What I want to do is break things down as much as possible so the details can be brought up. I will publish content regarding these headphones every day, until I think I have done a fairly decent post.

Box Contents

There is a "550" and "550-X" version. I strongly recommend going for the latter because of the Apt-X, which vastly improves the quality of the audio.

  • MM 550-X headphones
  • Documents
    • FCC radio statement
    • Safety Guide
    • Quick Guide, with CD
  • Rechargeable Battery 
    • Li-Polymer
    • BA 370 PX
    • 3.7V / 1.0Wh
    • Cover
    • Micro USB port, LED light
  • USB Cable
    • Type A (full USB) to Micro USB
    • 48 inches long
  • Power Adapter
    • Interchangeable with UK, UN, US, AU adapters.
    • USB port.
    • 5V, 1A
  • Audio cables
    • In-flight adapter
    • 3.5mm to 2.5mm stereo cable (56 inches long)
    • 1/4 stereo adapter.
  • Sennheiser bag
    • Main and secondary compartments.

Hopefully this gives you a better understanding of the contents of the package.


The MM 550-X is packed with features. They are NOT your normal headphones because of the different modes.

  • Wired (no enhancements)
  • Wired + Enhancements
  • Wireless (no enhancements)
  • Wireless + Enhancements

Sennheiser states that they weigh in at about 179g. I did NOT double check, but they do feel light.

The frame is very sturdy. The MM 550-X do grip your head quite strongly. If you compare the MM 550-X to Bose AE2s and QC15, you will notice how much "flimsier" the Bose branded ones are. For very long (10+) hours of use I would still prefer the Bose ones because I do not "feel" them on my head.

As you saw early on in the video the headphones can be folded, which makes them very convenient to pack.

The top band is leather and has very nice cushioning. The plastic sides are hideous and do attract scratches and other marks. (bad Sennheiser!)

Both the cups and pads are fine. The cups are of circular shape and are a bit deep. The pads are very soft and can be replaced.

One nice little touch that Sennheiser added is the "3 dots" on the left side of headphones. I believe this helps those who are blind recognize which side that cup is. (heaven points for Sennheiser)

Left Side Features
On the left side we can see a MIC and the battery. The right side also has a MIC. Both of these MICs are used for noise cancelling, Talkthrough, and to communicate through bluetooth.

The Battery is NOT always needed. If you want to use the Wired (no enhancements) mode then you do NOT need the battery. If you want to use enhancements and bluetooth you do need the battery. The battery is rechargeable through USB, which is more convenient than buying AAA batteries all the time. The battery can be replaced easily (do not force it).

Right Side Features
There are a lot of buttons on the right side. At first it may seem hard to figure the buttons out, but you do get used to them. Besides the buttons there is a 2.5mm stereo port, which can be useful when the battery goes dead.

Buttons And Functions
  • Volume Up, Down
  • Previous
    • Also works as rewind when held down.
  • Next
    • Also works as fast forward when held down.
  • Main Button
    • Turn On/Off (hold for 4 seconds)
    • Pair with bluetooth (from off, press and hold until it flashes blue and red)
    • Play/Pause music.
    • Answer call.
  • SRS
    • Tap to activate/deactivate.
  • NoiseGard
    • Press and hold (2 seconds) to turn on/off.
    • Tap to activate/deactivate Talkthrough.

Enhancements like NoiseGard, SRS Sound, and volume levels can be used simultaneously. I do like using some of the enhancements in specific scenarios. SRS will work very well for those over bassing movies, NoiseGard helps to reduce noise, and Bluetooth with Apt-X is such a joy. Anyways, I hope the video and the text description gives you an idea of the MM 550-X has to offer.


These are my opinions, this is by no means a "professional level" opinion. I do not expect everyone to like what I have to say.

At $500 these are some expensive headphones. Because of the price you would expect them to deliver a whole range of audio, but that is not always the case. There are dedicated headphones for specific purposes.

If you were to compare $20 headphones against $100 headphones, then you could notice a good amount of audio quality difference. When you go from $100 to $300 you also notice a quality difference, but the change is not as drastic. And when you go from $300 to $500 the increase in quality may or may not be as great.

There are several different modes in these headphones. These modes lead me to believe that the MM 550-X are more like multiple headphones in one package. The modes are listed above.

Because you can add enhancements the speakers are "powered". This added power may cause some "hissing" or "humming" and can be noticed when the audio volume is high on the headphone set. This humming/hissing is especially noticeable if you have "quiet" music. Of course there is a way to fix this, which is to increase the volume in the audio source (a computer), and then not have the volume in the headphones that high.

SRS Sound
SRS tries to have "surround" sound and "increases" quality. I do not think it works well with music, but it does work well with movies and games. Many movies have a lot of background sounds, these sounds can get in the way of the spoken words by the actors. With SRS the background sounds are diminished, and that allows the dialog to be heard (I love it). In games SRS enhances some of the small sounds, which gives you a better experience.

These are "active noise cancelling" headphones. This technology works by using the MICs to capture noise, create an opposite wave, and the processes cancels or diminishes the noise. The problem with the noise cancelling is that it DOES NOT BLOCK ALL sounds. On the product page, Sennheiser states that "NoiseGard 2.0 reduces up to 90% cabin noise", and the keywords are "cabin noise". There is a specific range of sounds that are reduced/cancelled, but it does not block every external sound.

VS Bose QC15
The QC15 sets the standard for "active noise cancelling" headphones. I think the QC15 are better than MM 550-X, but not by much. If you try the "test booth" at a store like Best Buy you will be impressed, but be aware of the increase in volume which also helps mask noise.

The volume on these headphones is suited for certain scenarios. If you were a DJ and you took the MM 550-X to a rave you would be very disappointed. These are NOT super loud headphones. If you took the headphones in an airplane, the office, or your not so loud room then the volume will be good enough.

There is some bass present, but it is not intensive bass. You can up the volume and get some bass, but the bass will feel weak when compared to Bose and Beats headphones

The mids/highs is where the MM 550-X do well. If you are seeking clarity, the MM 550-X will deliver.

Your Ears
When I was much younger I loved a lot of bass and loudness. As I have matured (only a bit) I have changed and now I prefer more clarity than bass. Of course I still like a good thumping in the ears, but not as much. Different people seek different things, and some seek clarity and others seek heavy bass. I do not recommend doing the loud thing for long, plenty of DJs have hearing loss because they love the loud stuff. Your ears change over time.

MM 550-X Wired
I would not recommend the MM 550-X because of the wired capability. There are plenty of high quality headphones that are lot less expensive.

MM 550-X Wireless
The magic of the MM 550-X occurs when you disconnect the stereo cable and allow the Apt-X + BT to work. Usually Bluetooth headphones sound like crap (they lose a lot of the quality during the compression/decompression), but the MM 550-X has more than just normal Bluetooth technology - it has Apt-X.

The claim of Apt-X is that it can do close to "CD level" quality through Bluetooth. Because I was very skeptic I thought that it was BS, all the wireless devices that I have tried always fall short. However, the Apt-X does really deliver near CD quality audio wirelessly. It is very impressive.

An added bonus of Apt-X is the reduction of the transmission delay. BT is notorious for terrible "video lip sync", but with Apt-X the delay is very small. I could not notice it.

The MM 550-X has Bluetooth controls, and this gives you some extra freedoms. You can change the volume, play/pause, previous/next, and answer call. I detest wires, and the wireless side really makes the headphones worth it.

VS Bose AE2
I have owned the Bose AE2 headphones for a while, and they have been great. Testing the Sennheiser MM 550-X for two weeks have created a little adjustment in my ears. After the two weeks I tried the AE2, and to my surprise the AE2 sounded "screechy", and very loud. It really made me appreciate the MM 550-X.

There are a few things that could be improved (as always), but if you want wireless headphones that offers very rich quality audio I would definitely recommend the Sennheiser MM 550-X.

I am conducting a few battery tests, and will post the results in a few days.

Battery Tests

Since this is an electronic device knowing the battery life is important. The battery goes by the name of Sennheiser BA 370 PX (which also fits in the PXC 310 Series)

Charge Times
I have observed that the battery's LED will take about 2 hours to glow from orange to green. Sennheiser states that the battery will fully charge in about 3 hours.

Charge tests (orange to green):
  • Power Adapter - 2 hrs
  • USB HUB - 2 hrs 9mn
  • USB PC - 2hrs 2mn

Conducting the charge tests was fairly easy, the discharge or "battery life" tests take a lot longer. The tests took a long time to conduct, but here they are. Enjoy!

Longest battery life test.
This is a very unrealistic case, you will not use it. The case involves being "wired", no enhancements (SRS and Noise Gard off), and volume to the lowest. The results were 14 hrs 18 mns. This is the most battery life you can get.

Airplane test
As you may know, you cannot be "wireless" on airplanes. So, for this case we will be "wired", Noise Gard ON, and volume at about 75%. The results for this test were 10 hrs 27 mns. This run time is enough for most flights.

In my room test
I like to have the headphones wireless, no enhancements, and volume at about about 50%. With this configuration you can get about 6 hrs 55 mns. The results are good, and I bet with reducing the volume level to 40% could get more battery life. If you compare the previous test you can notice the effects of "wireless" in the battery life.

Wireless + Noise Gard
On this scenario we are keeping the volume at 50%, using the wireless (bluetooth), and Noise Gard is active. The results were 6 hrs 10 mns. The effects of Noise Gard is a reduction of 45 mns.

Adding SRS sound does have an effect on the battery life. This case is the same as before but now with SRS activated, which gives 5 hrs 40 mns. A reduction of 30 mns of battery life.

Everything active + 100% volume
This is another unrealistic case, but it is the one that will drain the battery life the quickest. For this test the headphones were wireless (Bluetooth), volume at 100%, SRS and Noise Cancelling active. The results were 5 hrs 07 mns.

The battery is an essential part of the MM 550-X. As mentioned before, the magic of the headphones comes alive when they are wireless, which gives close to 7 hours. If for some reason this is not enough, you can always get an additional battery.

- What are the the differences of the "MM 550-X" and "MM 550-X Travel"?

I don't think there is a difference, and the "Travel" keyword is most likely a marketing move used in different countries/stores. In the USA the "Travel" versions of Sennheiser headphones are associated with noise cancelling features.

If you see a "MM 550" and a "MM 550-X" the difference would be Apt-X technology in the "-X" version. Usually there is a $120 price difference.

What I wanted to do is now complete. I hope the information is useful and answers your questions.

Since I bought these headphones for "testing" purposes I will now return them to the store... and go back to my lesser quality Bose AE2. The Sennheiser MM 550-X were a lot of fun, and if I could keep them I would.


VS Bose AE2

White Noise, Clicks, Humming

Almost every Bluetooth headphones/earphones that I have tried have noise issues: humming, clicking, white noise. Often reducing the volume on the earphones/headphones helps with this situation. However, there are technologies diminishing this issue. On my tests, the JayBird BlueBuds X did not have white noise. On the 550-X it is recommended that you do not have the headphones (when on Bluetooth) at full volume.


Can you connect the MM 550-X to a computer and use it with Skype?
When you use Bluetooth devices there are two modes. One of them delivers high audio quality, but does NOT support the mic. The other mode allows the use of the mic, but the audio quality is drastically diminished. You can only have one mode active, and you set it under the Windows Playback Devices.

How can I connect the headphones with my TV or home theater?
Get yourself an "AV/RCA to 3.5mm adapter" and an "Apt-X 3.5mm transmitter." There are other dedicated home audio systems that have Apt-X technology, which you can find by googling "List of Apt-X Compatible Devices."

Question about the noise guard. I just bought a MM 550-X. When I turn on the noise-guard, I could hear some humming noise only from the left headphone. Is that normal? Also, I won't be flying in the near future. Is there any environment I can create or go to so I can test the noise cancelling feature?
It is common for some electronics to have a humming on the side were the main electronics are, however the MM 550-X should have a uniform humming (both left and right should have the same). If you can, go to a store like Best Buy where they have a "Bose noise cancelling booth" and you can test it there. Regarding the noise on the left side, I would return that unit ASAP and get a replacement.

I just have a couple more questions. When I turn on just the power without using the cable, it's completely quiet. However when NoisGard is on like I said before there's a humming sound only from the left. And when I listen to music via Bluetooth with NoiseGard on, it sounds different. So my questions are, when NoisGard is on, are you supposed to hear the humming noise from both sides or nothing at all? Is NoiseGard supposed to change how the music sounds when on?
There is some humming going on when the 550-X are "turned on." The NoiseGard will add more noise. Usually this noise can be more easily noticed when up have the 550-X volume set high, my tip is to set it to more of a medium and then only manipulate the volume from the device (pc, phone, etc). If you hear the noise only from one side, the unit might be defective. On the video I did mention that each modification changes the way audio sounds, it's like 3-4 different headphone sets.

Hi, thank you for the video, beside the Bluetooth do you recommend Bose QC15 or the Sennheiser? thankx
It is not an easy answer, because I consider many variables. Price, comfort, audio clarity, batteries, and so on. Just keep in mind that if you get the QC15 and want the noise cancelling you need to constantly swap batteries (I think they are AAA), and the MM 550-X has a rechargeable battery (which is easy to recharge). I don't have a quick answer for you.

Thanks for this vid, I currently have the boise noise cancelling ones, not sure what model. I am after a wireless solution for playing music on my iphone, so BT sounds like the way to go, does that BT technology you mention work on iphone, is the sound quality good over T Secondly are they over the ear or on the ear cups, that bit is unclear to me. I want to use them at the gym so prefer on the ear, not as hot. Thank you.
As of right now I believe that you have to connect an Apt-X adapter to iOS devices, jaybird produces some of these adapters. While you do not need an Apt-X adapter for wireless/bluetooth, I highly recommend it to get the most audio quality. Bluetooth 2.1 by itself loses a lot detail. They are "around/over the ear" cups. I wouldn't recommend these for gym use... it's like buying a Lamborghini and then taking it off road. (hahaha)


  1. A timely review - I've been looking for some over-ear wireless headphones. I'll check back for updates as I've seen some people having issues with audio sync while watching videos via computer.

    1. Hi Jammy. The MM 550-X are more like "around ear" headphones. The "over-ear" are more like the Bose OE2 and Sennheiser PXC 310 BT.

      Bluetooth does have issues with "video lip sync". But the MM 550-X has Apt-X technology, which reduces this delay to less than 1.89ms (which is almost unnoticeable).

      I have my opinions video rendering and will post it within a few hours.

    2. I'm glad that these are faster than normal Bluetooth, but I don't suppose you have any idea what the actual delay with these headphones is (I'm assuming the 1.89ms figure comes from their website, and may not apply to a particular implementation of apt-x)? Sennheiser won't tell me, and yours is the only review I have found so far. Since I would be using these for gaming and music production, it's important to have very low latency (especially for music - any delay between playing a note and hearing it is very bad).


    3. Anything that is wireless will have a delay. The delay in these headphones is shorter than most of the other bluetooth devices, but I do not know the specifics. Previously I cited 1.89ms which is what is stated at http://www.csr.com/products/technology/aptx

      Since the headphones can also be "wired" the delay is very small. If you are looking for clarity then these are good headphones, for thicker bass I would check other headphones.

    4. Hi.

      Thanks for the info.

      I understand that the 550x hax Apt-X. But, for a apple fan-boy like me, can I take advantages of this technology. I know I can get a usb dongle for the computer, but can I get use of the tech on my iphone4?


    5. Mac OS X Lion and Snow Leopard systems have Apt-X supported, there is no need for a USB dongle.

      The iPhone does not support Apt-X, therefore you would have to get a transmitter. The two possible transmitters are 3.5mm transmitters and 30-pin iOS Device transmitters. You could use regular BT which should be ok, but it is not as good as Apt-X.

      List of compatible Apt-X devices:

    6. Thanks a lot...

  2. Hi Jesse, one question, I can find MM 550 (not X) for much less then X (let's say € 270 vs € 400), do you believe it worths the difference?

    1. The wireless (bluetooth) audio quality is very different in the MM 550 when compared to the MM 550-X. The MM 550 is missing Apt-X,, this is the special feature that makes the 550-X wireless audio quality way better.

      If you have seen the Opinions you know my position on the just the "wired" part of the 550-X, basically get something else that is less expensive and most likely will be better. The 550-X is for wireless audio, and it does a very good job at it. (3m)

    2. I'd like to take the PXC 360 wired but it's more expensive then the 550! What do u suggest as wired noise cancelling then Bose?

    3. When it comes down to Active Noise Cancelling I have only tried the Bose QC15 and the Sennheiser MM 550-X. If I was looking for alternatives I would use Amazon and Google Shopping to view other options:

      Usually "active noise cancelling" are fairly expensive compared to the other headphones. (3m)

  3. Question, does the MM 550-X work w/ Android 4.0 ics?

    1. If the Android device has Bluetooth, then yes. But remember that "Bluetooth" and "Bluetooth with APT-X" is different.

  4. Does that make a difference in sound quality?

    1. Yes. The whole point of getting the MM-550X is to get Apt-X technology, which improves the audio quality a lot. They claim up to "CD level" quality over wireless. By the way... you would also need high quality music files to fully appreciate the Apt-X.

      Most mp3 files are compressed (and most times they lose the tiny details that make music great), the audio found in CDs are not as compressed and can be saved as high quality .wav files.

      The problem with having CD level audio quality is that it takes a lot of storage. Usually a CD album needs about 500 MB, an mp3 album (at highest quality) may require less than 100 MB. Most people have been conditioned to hear lower quality music (thanks to Apple/Youtube/Amazon/Microsoft/Internet).

      Usually musicians hate music compression. They usually capture/produce high quality music samples, edit them in high quality, render them in high quality, and then music stores compress the hell out of them (for convenience) and a lot of details are lost. Even vinyl records (the old black discs from 20+ years ago) have more detail in them than most high quality mp3s.

      Perceived audio quality = condition of your ears + headphones quality + wired/wireless tech + pc/music player compression/decompression + music file quality.

      That's the basic formula. Yes it can become more complicated once you start to add mixers, amplifiers, the materials of the cables and speakers, etc. So... this is why going into the "audiophile" route is extremely expensive.

      To get a $500 headphone set can be a waste of money because you need to consider all the variables that affect quality of audio. That's it for now. (16m)

  5. Final question: Is there a huge difference in sound quality between the APT-X and the regular BT, or is it just barely noticeable?

    1. I can notice the difference, and I'm not a trained musician. Bass is one of the sounds that is affected by the compression, and usually loses it's "punchiness". If you are in your 20s+ and have paid attention to the music's details then you will notice it. The mp3 generation has missed out on a lot of great audio quality, and therefore are "untrained" and will probably not notice the loss of quality as much.

      Going to a live orchestra and listening to an mp3 of the orchestra is a very different experience.

  6. What is the deference between the 550 and the 550-X?

    1. I think the difference is the Apt-X technology, or it might just be the noise cancelling capabilities.

  7. Hey Jesse,I consider buying these or the IE80 for my iPad.I love these but I've heard that the volume limitation is too low.which one should I go for?

    1. I wish I could give you a definitive answer, but I cannot since I have not used the IE80. Amazon currently has about 11 reviews, so maybe you can find some answers there.

    2. I am planning to Purchase the MM 500 x not 550 x Both arr apt-X and compatible with my Samsung Galaxy S3!Its a cheaper alternative and does not have Active Noise cancellation or SRS wow!

  8. Thanks for the review(s) - for me I need noise cancelling for the various trains I use, and bluetooth for the lack of wires.

    I currently have Nokia BH-905i headphones (also noise-cancelling & bluetooth) but one of the ear pads has ripped and emailling Nokia support shows that you can't get spares for them! they need to go back to a repair centre, and the repair is likely to cost as much a new pair, so Nokia have lost a customer.
    The fact that the Sennheisers fit over the ear also mean that I won't be hearing the wind and other external noises as much when I am walking.

    The only aspect of the Sennheisers that I would like to find out more about is what they look like on a head, since they seem to stick out quite a lot and I'm worried about catching the headphones with my rucksack strap when I am putting it on and taking it off.

    What I need now is for the price to come down to a reasonable level :-)

  9. Thanks for your nice test.

    One question.
    How do this MM 550-X working in noise environment and to recieve a phone call?
    Will the people in the other end hear all noise around me or does the noise cancelation help so that I can take phone calls in the subway in a good way, both for me and the caller at the other end?

    1. The listeners would hear the ambient noise going around you when you answer calls.

    2. Thanks for your reply.
      To bad that the Microfones does not minimize the suronding noise, so that it does not get through to the other end of the phone call. :(

      I gues I then just need to write to them and request this function. :)

    3. Thanks for your reply.
      To bad that the Microfones does not minimize the suronding noise, so that it does not get through to the other end of the phone call. :(

      I gues I then just need to write to them and request this function. :)

  10. Btw. Forgot to ask if you do know the differens betwen "MM 550-X" and "MM 550-X Travel"?
    Clearly the "Travel" one is more expensive...

    Just wish that Sennheizer would get a better home page where it is easy to compare all the different models and what functions they got.

    1. I don't think there is a difference, and the "Travel" keyword is most likely a marketing move used in different countries/stores. In the USA the "Travel" versions of Sennheiser headphones are associated with noise cancelling features.

      If you see a "MM 550" and a "MM 550-X" the difference would be Apt-X technology in the "-X" version. Usually there is a $120 price difference.

  11. Thanks so much for this very complete review :)

  12. great work Jesse!
    I almost agree with all your observations on the Sennheiser MM 550-X. I have them for 1 month and I'm really happy. They are a bit expensive but, most probably, the best Bluetooth on the market (I didn't check the Parrot Bluetooth).
    Keep on!

  13. EXCELLENT review Jesse.

    I bought these and after having tested them for a couple of weeks, I have come to the same conclusions as you.


  14. Hello Jesse,
    Thank you for this review! I have a question, I am looking in to a pair of headphones such as this one, however they are quite expensive. I intend to use these primarily for music and calls. Other than the lack of active noise cancelling (which I do not think my life style requires) and SRS (a feature which I find near pointless) do you think their would be any advantages in buying the 550-X as opposed to the 500-X?

    1. I'm glad you have priorities and have evaluated each headphone. The main reason that explains a 550-X purchase is because of the noise cancelling. If you don't need noise cancelling then the 500-X seems like a good choice. This should save you some money, and I would also check online for coupons.

  15. Hi Jesse,
    Do you think they are worth it for 300 $. If so i will buy them from amazon.

    1. Considering all the capabilities of the 550-X I think they are completely worth the $300.

    2. Hello Jesse,
      I bought this head phones from amazon a week ago, and I am really annoyed by the hissing noise. This is my first noise cancellation headphones so I was wondering if your version make the noise or just mine? if so thn is all noise cancellation headphones make that noise or just this Sennheiser MM 550-X Wireless Bluetooth?
      Thanks for the awesome review

    3. Not all battery powered headphones/earphones make the white noise, but most do. The MM 550-X do make noise, especially if you have the 550-X's volume levels at max. I recommend lowering the volume in the 550-X and increasing it on the audio source (laptop/pc, phone, media player, tablet).

      From several headphones/earphones that I have tried only the JayBird BlueBuds X do not have white noise.

  16. Hey Jesse,

    I'd really like your review and i got one question.

    Can 550-x be paired simultaneously with computer and smartphone, so we can switch between skype calls and phone calls ?

    Best regards.

    1. It cannot be paired to two devices simultaneously; I wish it had such a feature.