Review: Sennheiser CX 400BT – Compact Audio Excellence

Healthy competition in consumer electronics is a great thing. Without it innovation and advancement of technology and products would languish in no-mans-land.

The wireless in-ear headphone (earphones) market would be very dull without the millions – if not billions – of dollars invested by the likes of Apple, Sony, and Beats over the past twenty years.

Thankfully whilst these companies were diversifying into every market segment they could find such as gaming, mobile phones, and tablets, Sennheiser stuck to what they know and do best and quietly and profitably designed and manufactured some of the best headphones and earphones available today. I still remember the design and sound from the yellow Sennheiser headphones in Business Class on Cathay Pacific flights in the 90s.

And today with the advances in wireless Bluetooth connectivity, the quality and functionality of small, high-quality earphones is booming and Sennheiser have recently introduced a formidable contender – the CX 400BT True Wireless earbuds.

The CX 400BT earbuds come in a small but robust charging case that with the earbuds can give you up to 20 hours of battery life – 7 in the earbuds and another 13 in the charging case. Charging time is 1.5 hours for a full charge or 10 mins for 1-hour playtime via the USB-C port at the back of the charging case. A small button on the case allows a quick check of the battery health at any time. A very useful feature.

Download the Sennheiser app for iOS or Android to give you complete control over your earbuds. Firmware updates as well as complete customisation are available via the app.

The CX 400BT earbuds themselves are very well proportioned. Unlike the very generic fit of other wireless earbuds, the Sennheisers encourage a ‘twist-to-insert’ motion that maximises comfort and sound quality.

Once in your ears, the Sennheiser app helps with Bluetooth connectivity and then unlocks a number of customisation and sound quality features. You can individually program the single, double, and triple taps of each earbud to perform the tasks you want from Next Track on your music to activating your preferred Voice Assistant on your smartphone.

The other highly praised feature of the Sennheiser CX 400BT Earbuds is the wide range of audio codec support including SBC, AAC and aptX, meaning premium sound is guaranteed with any mobile device.

The Passive Noise Cancellation is more effective that you might expect and in all but the closest and loudest sounds. Noting beats Active Noise Cancellation, but this is very good for the pricing of the CX 400BT earbuds.

Sound quality is exceptional for the 7mm dynamic sound driver that is contained in each of the 6 gram earbuds. The Equaliser feature in the Sennheiser app lets you customise your listening experience with surprising precision.

My only criticism of the Sennheiser CX 400BT True Wireless Bluetooth Earbuds is that the touch sensitivity of the earbuds is too sensitive. I found on a number of occassions trying to find the left or right earbud with my index finger would trigger the Music Stop command when I wanted to Skip to the next track.

On the positive side, I do like that the CX 400BT Earbuds don’t cut the music when you take one out of your ear meaning you can have a quick conversation with someone and then get back to your music.

These are definitely worth a look if you are in the market for some reliable, long lasting and high quality in-ear sound this holiday season.

Available in Black or White the Sennheiser CX 400BT True Wireless Bluetooth Earbuds are priced around $299.95 from Sennheiser or Amazon.

About Author
Mike is the Australian editor of with a lifelong passion for cars, technology and engineering. He reviews and writes about all kinds of motoring and tech products for our readers. Follow Mike on Instagram or send him an email: