Best Mobile Headphones - Sennheiser MM 400-X Bluetooth Review

How many pairs of headphones do you own?

My best friend must own over 10 now - all in regular use. This has to be too many, although he’s happy, so who am I to argue?

How many is too many?

I used to think it was one pair. That pair for me was the AKG K550. Huge, but comfortable. I can, and do, wear them all day and the sound is about as good as it gets without buying open backed ones and ensuring everyone around can hear your music too.

Trouble is, they’re not much good down the gym. Come to think of it, they’re not much good for walking about either. That 3m thick cable would probably trip you up as you try to cross a road for starters.

To my mind, you can definitely justify two pairs. You want the best you can for home/work and a second set for listening on the move.

The original Sennheiser Momentums are, to my mind, the best mass market headphones around

Whilst Sennheiser will help you part with north of €50,000 for their best effort (check out the Orpheus here) - for the masses, I would recommend the Sennheiser Momentums (the original pair, now much cheaper) as the best for home listening. I wrote about them when I felt like a rant about the popularity of Beats headphones, back when they were bought by Apple. Comfortable for hours, lovely detail with enough warmth to suit most tastes without you thinking it’s all getting a bit artificial.

When it comes to mobile headphones, compromises must inevitably be made to the sound quality. They need to be physically smaller and lighter for a start and you may want them to fold into a space in your bag or pocket. This means the drivers need to be smaller and lighter, which in turn means less of our favourite thing; bass.

There’s one final compromise that can really help the convenience of mobile listening, but in the past has been a step too far for those who want good sound quality. You can ditch the cable and buy yourself a pair of bluetooth headphones. I’ve decided it’s the right time to do that.

The Sennheiser MM 400-X bluetooth headphones came out in 2014 and are part of a range of models, peaking with the MM 550-X.

Originally £180, the 400’s are now well under £100 on Amazon and given the reviews of the time, they represent phenomenal value. For the money, you get a very lightweight pair of folding ‘on-ear’ headphones and a case for them to be protected in when you travel.

The ear pieces are clamped firmly to your head, with a nice soft leather-like cushion which I found remained comfortable for about 2 hours of constant use. The tight fit might not be to everyone’s taste, but it definitely keeps them stable on a brisk walk and it also helps keep the noise of the street out of your tunes, without you needing to blast your own head off.

The left ear-piece holds the removable battery, which is rated at 20 hours of use and should last for at least 2 years. This is good news in an age of smartphones and laptops where the batteries are sealed in, effectively condemning them to landfill after a comparatively short life. True, smartphones can be rendered technically obsolete in that time, but headphones should enjoy a long life and still keep up with the new kids on the block years after purchase. The disappointing news is that the batteries are surprisingly expensive at £40 each.

If you don’t want to buy a spare battery to extend your wireless listening time, you can connect the supplied audio cable to the right hand ear-piece and use them as a traditional pair of cans. There’s even a zip compartment in the case to keep them together.

The right hand ear-piece also houses all the bluetooth technology that enables wireless listening along with some controls that you can use to adjust the volume, skip forward and back or play / pause. The more eagle-eyed of you will also notice a smaller hole, just round from the headphone jack. That’s a mic and it means you can have a hands-free conversation, should a call interrupt your tunes. I’ve only used it once, but found it worked well (if a bit distant compared to using the phone on its own).

Overall, the build quality is as good as you would expect from a top brand like Sennheiser and they fold down conveniently enough to fit in a bag. In fact, my only real criticism is that if I try to wear them round my neck when not in use, they do rather try to strangle me - so I have to take them off and put them away in between sessions.

I’ve gone on far too long talking about headphones without mentioning how they sound. Well, given the compromises, I’m very impressed indeed. Using my Samsung Note 3 and Spotify, I cannot tell the difference between the bluetooth connection and the cable - so wireless has definitely come of age, at least for smaller cans.

Detail is incredibly good and there is plenty of energy and punch in dance and beat-heavy tracks. If your main pair are of the quality of the Momentums, you will notice a relative lack of bottom end when it comes to rock and classical. But that’s not to say that it’s a tinny experience, far from it and the decent stereo separation go a long way to making up for it if you’re feeling critical.

The Sennheiser MM 400-X headphones make for a great choice for those looking for a decent pair of headphones for use on the move, or for stowing in your bag for grabbing occasional musical escapism. If you travel on the trains and planes a lot, then it may be worth considering the MM 450-X, which are exactly the same, but include noise cancelling technology. I’ve had five minutes with a pair and was impressed, but I couldn’t justify the price difference.

Finally, if you’re a believer in only owning one pair of cans, then you could certainly do worse - but you might be able to do a tiny bit better too. I had a bit of a face off between these and the Plantronics Back Beats. The plantronics had a fuller sound and were lighter and more comfortable, for very similar money. They don’t pack away quite as conveniently and would be the first to fall off your head in a dancing competition, but they’d be a good set to compare against before you spend your hard-earned.