sennheiser cx 400 bt, headdphones, earbuds, reviewNot long after the launch of Sennheiser Momentum 2 truly wireless headphones, Sennheiser’s new Sennheiser CX 400BT Truly Wireless Headphones landed on my desk. These wireless earbuds look very similar to the MOMENTUM 2; so what’s the difference between them, and what are the CX 400BT like to use? I’ll share what I learned in this review.

Sennheiser CX 400BT truly wireless headphones review

Sennheiser CX 400BT truly wireless are a premium earbud style Bluetooth headphone, with a charging case.

sennheiser cx 400 bt, headdphones, earbuds, reviewWhat’s in the box?

  • CX 400BT truly wireless earbuds
  • Silicone ear adapter sets (XS, S, M, L)
  • Charging case
  • USB-C cable
  • Quick guide & safety guide

Sennheiser says these earbuds are made for listening to high-quality audio detail of your favourite music, audiobooks, and podcasts on the go while staying connected to incoming calls and your loyal voice assistant. The earbuds are designed to fit snugly into your ear to block out outside noise.

It has an extra-long battery life and several customizable and integration features that put these wireless headphones in a completely different category of portable sound technology.

Sound specs

Sennheiser CX400BT’s 7mm dynamic drivers ensure that the earbuds deliver outstanding stereo sound thanks in part to an internal audio EQ, and by the latest Bluetooth 5.1 technology, AAC and aptX compatibility.

sennheiser cx 400 bt, headdphones, earbuds, review

What’s the difference between the Sennheiser MOMENTUM 2 and the Sennheiser CX 400BT? 

The CX 400BT have many of the same amazing features of the MOMENTUM truly wireless 2. These include those 7mm dynamic drivers with a built-in equalizer, an ergonomic design, customizable touch controls, calls and voice assistant access.

The MOMENTUM Truly Wireless 2 add enhanced features such as Active Noise Cancelling & Transparent Hearing, smart pause (where the earbuds pause the music when you remove them from your ears), and IPX4 splash resistance.

They also offer a 28-hour battery life, compared to 20 hours for the CX 400BT truly wireless and the MOMENTUM 2 have fast charging. The MOMENTUM package is also a little more stylish, with its fabric wrapped case, and the MOMENTUM buds have a bit of a softer, rounder design, while the 400BTs are more boxy.

Despite those differences, the new CX 400BT truly wireless use the same acoustical system as the MOMENTUM truly wireless 2.

So in a nutshell, all the same sound quality, but missing a few key features.

sennheiser cx 400 bt, headdphones, earbuds, review

Fit & feel Sennheiser CX 400BT

These earbuds do have a slightly bigger and boxier profile, but they look similar to the MOMENTUM. With several sets of ear gels, you can customize your fit so it’s pretty comfortable. They don’t feel too big in my ears. These buds, once paired will also connect quickly to the last device you paired them to, meaning when you put them in they’re always ready to go.

While there’s no active Noise Cancelling, these do a good job of achieving a sound isolating fit that’s able to block out outside noise by forming a good seal inside the ear.

Sennheiser CX 400BT sound quality

Let’s dive right into how these sound. Some of the main audio features include:

  • Transmission for a variety of audio codecs including SBC, AAC, and aptX
  • Built-in equalizer, which you can utilize to customize the sound to your preferences via the Sennheiser Smart Control app for IOS and Android
  • 7mm drivers which provide the incredible audio quality

I tested the new CX 400BT out with a variety of music… If you want to check out my test playlist on Spotify it’s linked up here.

The bass on these is outstanding. I put on the bass-heavy Hypnotize by Notorious B.I.G. and started groovin’. There’s intensity and resonance in these earbuds and they give you a good thump. Even so they’re extremely well balanced. The vocals are clear, and the treble and the highs aren’t tinny or raspy.

Having spent some time with the MOMENTUM 2 recently, I can definitely say these deliver on premium sound quality, and match the MOMENTUM 2s beat for beat.

sennheiser cx 400 bt, headdphones, earbuds, review

Key features

Truly wireless & connectivity

CX 400BT truly wireless connect to your phone, computer or audio device via Bluetooth technology (5.1) within up to a 10-metre range.  I tested these out by wearing the buds and walking away from my phone and there was no breakup or dropouts.

Customizable touch controls

There’s no buttons on these earbuds – you can control your music, virtual assistant, and calls by tapping the right or left bud. You can leave the standard tapping controls as is, or you can customize the touch controls on the Sennheiser Smart Control app to suit what is most intuitive to you.

The touch controls worked well and I found the boxier shape actually helped me hit the touchpad a little more precisely.

sennheiser cx 400 bt, headdphones, earbuds, reviewSennheiser Smart Control App

Inside the app you can manage your headphone settings. You can customize your touch controls here and adjust equalization settings to your preference.

Setting these earbuds up, by the way is quick; take the buds out of the case and push and hold one of the touchpads. You’ll hear it say, Pairing.

Go to the app and start the pairing process and you may need to go to your Bluetooth settings to confirm the connection, outside the Smart Control app. From there, they’re ready to go. You can re-pair by pressing and holding both earbuds’ touch controls at the same time.

Worth noting is that I needed a firmware update when I paired them. Initially the app told me it would take almost 50 minutes, but you can keep listening to them while the update happens.

You can also simply use the pairing process to connect your buds to your phone using Bluetooth and run it without the app.

sennheiser cx 400 bt, headdphones, earbuds, review

20-hour battery life

The portable charger that doubles as a carrying case keeps your earbuds safe together and stocked with power when they aren’t in your ears.

The batteries are said to be “all day” batteries with a 20-hour battery life per charge. The 20 hours of audio time include 7 hours of life in the buds themselves plus 13 hours of additional battery in the portable charging case.

Digital assistant and phone call features

The headphones include an integrated microphone and touch controls to give you easy access to Google Assistant and Apple Siri voice assistant in addition to phone calls if you have connected the buds to your phone.

You can access digital assistants, answer and hang up phone calls with specific tapping patterns on the assistants.

Overall review of Sennheiser CX 400BT wireless earbuds

These earbuds are a great buy, in my opinion. They deliver on great sound quality, and at a substantially lower price that the Momentum. They fit well, they’re compact and the battery life is great. You can also use just one bud at a time if you like.

While the Sennheiser CX 400BT headphones have many great design and sound features, they have a few drawbacks.

They are not weatherproof or water-resistant, there’s no auto-stop or auto-resume features when you take them in and out of your ear, they also lack noise cancelling and ambient mode. Now the good news is that if those features are important, you can get them by upgrading to the MOMENTUM 2.

If you’re looking for premium headphones with top notch audio at a great price, you’re going to want to check out the Sennheiser CX 400BT Headphones and you can find them at Best Buy.

Editor TV and Home Theatre
Erin is a journalist, writer, and TV producer with a fascination for technology and a love of gadgets. Check out her blog