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Thanks to Sennheiser for sending us over these CX 400BT True Wireless earbuds. At the time of this review, the price has been reduced from €199 to €169 and if you know someone in your life that likes listening to music and you’re stuck from a present for the holiday season, these are a definitely up for consideration.


The CX 400BT True Wireless (their full name and not sure if the marketing department was off that day) comes in two colour options, black or white. They are a more distinctive design looking like little cubes when they are sticking our out your ears, and they will stick out. I’m OK with this, you’ll never see them and sometimes it’s good for members of the public to see that you’re not listening to them because you’re listening to whatever audio tickles your fancy.

Sennheiser CX 400BT True Wireless in the ear

Sennheiser CX 400BT True Wireless in the ear

Even though the buds are large they are not heavy. Weighing in at 6 grammes each, you can go a few hours without getting strained. The case is also on the large size. When you compare it against the number 1 selling buds in the market, The Air Pods Pro, you can really see the difference. You can pocket them but it will cause a bulge.

Sennheiser CX400BT case vs Apple Air Pods Pro case

Sennheiser CX400BT case vs Apple Air Pods Pro case

Battery Life

From a full charge, you’ll get around 7hrs, the case will give you another nearly 2 full charges and that is where you get the 20 hrs on the promotional video below. it takes 90 mins for a full charge.


We have some good and some not so good features. Let’s start with the good. The pairing process was nice and simple by just pressing both buds for 3 seconds and you can connect them to what you’re listening too. I have them linked to my android phone and apple laptop. No issues. The touch based actions are great with single, double, triple and long press actions prebuilt in but where these buds really stand out is that fact you can customise these.  Note that the call answering functions are not customisable.

The app is very user friendly to use. Customising the touch controls was super easy and you even have the option to turn off touch controls. The audio is a good as the more expensive Sennheiser Momentum True Wireless 2 earbuds because it’s the same 7mm drivers inside. In the app you also have an equaliser that you can play around with to get the tunes to sound how you like them. These earbuds use Qualcomm® aptX™ and when using devices that support this, the sync when watching video was perfect. Like other Bluetooth devices that don’t support this, the lips won’t match the words. The case is USB type c which is included in the box but with everything else nearly charged via type c nowadays, this is making carrying one charger around so much handier.

Sennheiser Smart Control App

Sennheiser Smart Control App

And now those features that could be improved. There is no water or sweat resistance so don’t get caught in the rain or go buying these for the gym. When I first powered and connected the buds to my phone with the app, like most new devices, there was already a software update to install. The app said it would take approx. 20 mins but it took 2 hrs!. I had to keep the app open and the buds out of the case. I know (well I hope) this won’t be a regular occurrence, but it did leave a small negative in my mind.

There is a 1 sec second delay when using the touch controls which doesn’t sound like much but in 2020 and going into 2021, it feels a little too long for me. There are no sensors in the buds so your audio won’t stop or start if you insert or remove the buds from your ears. For this price, the Sennheiser CX 400BT True Wireless earbuds don’t come with active noise canceling and it’s just passive noice cancelling (how well you and seal them in your ears).

The case doesn’t have any LED’s to show you that the buds are charging, just that the case is charging when you plug it in.


Not a bad effort. Not the cheapest buds but I feel you get what you pay for. The sound quality is good and so is the battery life. Competitors are the Samsung Galaxy Buds Live (aka: the Bean Buds) which Tony on the team has reviewed here. They would also go up against the Jabra Elite 75T which John on the team has reviewed here. If I was asked about earbuds in the price range, I’d be happy to throw these into my mix of possible choices.

Derek Reilly

EV Contributor at TheEffect.Net - Founder of the Ireland's №1 EV YouTube channel EV Review Ireland - Set up the Dublin EV Owners Club - General Manager at - Mayo man in Dublin

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