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REVIEW: Sennheiser CX 400BT True Wireless Earbuds – Do They Deliver?

There is a plethora of true wireless earbuds out on the market now, and users are finding it hard to wade through the cheap and nasty to find true quality sound.

Sennheiser is known for sound and its new CX 400BT earbuds are a reliable addition to its suite of audio products.

At $299, it’s a high price which doesn’t always reflect the look, feel or battery life. But it does have several positive features which makes it a good pair of mid-tier earbuds.


The design of the CX 400BT earbuds is quite basic. I was weary of the square shaped outer-ear part, but once fitted into the ear it was comfortable and sturdy.

The buds are small and compact, nothing too fancy despite its price tag. The 37g charging box is also pleasantly small, good for easy transportation or to shove in your pocket.

They sit nicely once inside your ears and after a few hours of use I didn’t notice any pain or aggravation, which isn’t surprising given they weigh a tiny 6g each.

While the buds are little, Sennheiser designed it so there’s a fair amount of room for the touch controls to work well without fiddling around.

Sennheiser gives users four size options for the silicone bud covers too, so you can customise how comfortable the twist-to-fit function is for you.


The audio is clear, rich and without crackling or buzzing even when at full volume.

When playing bass-heavy songs or dynamic instrumental sound it didn’t waver. I tested quite a few different songs and nothing was compromised and it shaped the sound beautifully.

The CX 400BT earbuds don’t have full active noise-cancelling like its older brother the Momentum True Wireless Two, but with the twist-to-fit design and the sound quality, it does the job fairly well anyway.

The response time between phone-to-earbud is a little delayed sometimes, especially when flicking through songs. I also found there was a slight delay when using the touch control to pause, play or skip songs.

Sennheiser’s big drawcard for its earbuds is the Smart Control app, which users can play with to change EQ adjustment and to customise the touch controls.

Customising functions is a big bonus, especially if you’re not fond of the default settings or if you use the earbuds for a lot of calling.


The CX 400BT has all the necessary features to bump it into the $200+ market, including Google and Siri Assistant.

The Smart Control app allows you to customise how your phone call experience is with the earbuds. When using the call function, I could ear the person on the other end loudly and clearly.

A nice little feature is the auto-accept call, which accepts incoming calls but taking the right earbud out of the charging case.

If you’re having issues with Bluetooth connectivity – which I didn’t – you can factory reset the headphones and start again too via the app.

When it comes to Bluetooth, it was nice and easy to connect my CX 400BT earbuds to both my phone and my laptop. There’s a 10m range too, so while you’re walking around the room or house with the buds still the music will still play.


The CX 400BT earbuds have 20 hours of battery life on a full charge, which isn’t overly impressive when you compare it to a lot of others on the market.

It just means you’ll have to charge the buds once every two days or so.

It also takes 90 minutes for the buds to be charged back to 100% in the case, which is a long waiting period.


The CX 400BT True Wireless earbuds aren’t the crown jewel of Sennheiser’s headphone range, but it’s a quality product with good sound and an unintimidating design.



Good sound

Comfortable fit

Responsive touch controls

Useful Smart Control app


Battery life


High price

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