Sennheiser CX 400BT True Wireless review: Enjoy excellent audio for less

Sennheiser’s existing True Wireless earbuds – that’s the Momentum TW (True Wireless) and Momentum TW2, for the uninitiated – are both exemplary of the high standards you’d expect from the German audio manufacturer, offering superb sound quality and solid connectivity. The Sennheiser CX400 BT True Wireless, which follow quickly on the heels of the Momentum 2, deliver much the same experience as their pricier stablemates, albeit without the frills.

Sennheiser CX 400BT True Wireless review: What do you get for the money?

Unlike the Momentum True Wireless 2, this new model has no active noise cancellation or transparent hearing mode. There’s also no auto-pause function and no splash proofing, meaning you should avoid using them in the rain or during particularly sweaty exercise.

As you might expect, given their lower price of £170, the earbuds and their plastic charging case also feel a little less well built than the Momentum 2s. They have the same familiar touch-controls on each earbud, though, which let you control your music playback, interact with your phone’s voice assistant and take calls. And, as with the other models, the charging case charges via a standard USB-C cable.

In terms of battery life, the CX400BT True Wireless promise up to 6.5 hours playback from the batteries in the buds, which can be extended by an additional 13.5 hours (20 hours total) when using the carry case to recharge them. That’s a big improvement on the first-gen Momentums, which offer a rather paltry 12 hours of total battery life, but less than the Momentum 2’s impressive 28 hours of usage time.

Besides these differences, the experience is more or less identical to what you get with the rest of the range, with the Sennheiser Smart Control mobile app giving you control over the headphones’ equaliser and touch control customisation.

Sennheiser CX 400BT True Wireless review: What are they like to use?

Despite having a very slightly larger housing than the Momentum 2s I quickly achieved a snug, comfortable fit with the CX400BT True Wireless. Pairing, too, was easy and I found the slightly larger surface area on the touch sensors made controlling the headphones a little less finicky than their pricier stablemates.

I did, however, feel the absence of the handy auto-pause mode, especially since there’s no transparent hearing mode as you find on both generations of the Momentum True Wireless. If you want to have a quick chat with someone, this means you’ll likely have to tap the left earbud once to pause your music and then remove it so you can hear what they’re saying. That feels markedly less immediate than simply removing an earbud and the music pausing instantly.

Thankfully, any shortcoming in this regard is made up for by the superb wireless performance of the earbuds. As with the Momentum 2s I could move freely about my house while leaving my phone in an upstairs bedroom and the earbuds would never so much as miss a beat. Depending on the thickness of your walls, the performance may not be quite this good but the CX400BT True Wireless have very good Bluetooth range indeed. I had no problems with a single earbud dropping out, either, as can be the case with some true wireless earbuds.

Sennheiser CX 400BT True Wireless review: How do they sound?

As for music reproduction, the CX400BT support SBC, AAC and AptX codecs via Bluetooth 5.1 and, impressively, considering they cost £110 less than the Momentum 2s at launch, you’d have a difficult time separating the two models when it comes to sound quality.

Since they have the same 7mm dynamic drivers as their pricier stablemates, you might argue that’s not altogether surprising, but I was nonetheless pleased to hear the CX400BT True Wireless deliver the same impressive sense of space and instrument separation that the Momentum range have been lauded for.

If there’s any clue that the CX400BT’s are a different set of earbuds when they’re in your ears, it’s that they are a little more forward when it comes to their handling of the upper registers. On Mobb Deeps’ Can’t Get Enough of It, the (admittedly grating) vinyl crackle has a particularly harsh quality to it.

For most recordings, this treble-forward reproduction simply wasn’t a problem for me, but occasionally, those with more sensitive ears may find themselves looking to dial back the treble from using the Smart Control app on bright-sounding tracks. Otherwise, I have absolutely no complaints when it comes to the CX400BT’s audio quality. They have a delicate, detailed mid-range and generate bass in a way that’s prominent without ever sounding overbearing. In other words, they’re a delight to listen to.

Sennheiser CX 400BT True Wireless review: Should I buy them?

I’d have no hesitation in recommending the CX400BT to anyone looking for a pair of true wireless earphones that have superb sound quality, solid battery life and top-notch connectivity. They’re a superb-sounding pair of true wireless earbuds. However, that recommendation comes with a couple of caveats.

First, if you’re happy to forgo the improved battery life, you can now pick up the brilliant-sounding Momentum True Wireless for £150. These have a transparency mode and IPX4 splash resistance, making them arguably the more practical choice for everyday use outside the home.

The other slight catch is that there are a great number of other true wireless earbuds in this price bracket vying for your attention, including Sony’s brilliant WF-1000XM3 which offer mammoth 32-hour battery life and active noise cancellation. If you want the full package, therefore, you may be better off looking elsewhere.