The Sennheiser CX 400BT True Wireless are sleek in-ears that resemble the Sennheiser MOMENTUM True Wireless 2 in look and performance. They have a similarly warm sound profile and can passively isolate as much noise as their ANC-equipped relative. If you prefer a different sound, their companion app offers a graphic EQ to adjust them. However, they have a disappointing battery performance. Still, if you're looking for a pair of well-built and customizable truly wireless headphones, they're a solid choice.
Our Verdict
The Sennheiser CX 400BT are alright for neutral sound. They have a warm sound profile that lacks a bit of low-bass. There's also a dip in the low-bass, which veils vocals and lead instruments. Due to their in-ear fit, their soundstage is very closed-off. On the upside, they deliver audio consistently and their companion app offers a graphic EQ to customize their sound.
- Graphic EQ available.
- Disappointing battery performance.
- Bulky design.
The Sennheiser CX 400BT are decent for commute and travel. They're fairly comfortable and very portable, but they struggle to cut down bass-heavy noise like bus or plane engines. Their roughly five hours of continuous battery life also may not be long enough to get you through a long flight. That said, they're well-built and their carrying case offers around two additional charges.
- Great build quality.
- Disappointing battery performance.
- Bulky design.
The Sennheiser CX 400BT are very good for sports and fitness. Even though they don't have stability fins, they're lightweight and feel stable enough for moderate exercise. There's no cable to get caught on something while moving, either. However, although they're fairly comfortable, they have a bulky design that sticks out of your ear. They also don't have an IP rating, though we don't currently test for this.
- Great build quality.
- Stable in-ear fit.
- Disappointing battery performance.
- Bulky design.
The Sennheiser CX 400BT are alright for office use. They're fairly comfortable and they can reduce an impressive amount of ambient chatter. Their leakage is quite low so you shouldn't bother people around you if you're listening to audio at a high volume. However, their battery life may not be enough to last a full 9-5. Luckily, the carrying case offers around two additional charges.
- Great build quality.
- Disappointing battery performance.
- Bulky design.
The Sennheiser CX 400BT aren't suitable for wireless gaming due to their high audio latency when connected to Bluetooth-enabled PCs. They're also incompatible with PS4 and Xbox One consoles.
The Sennheiser CX 400BT are Bluetooth-only headphones and aren't compatible with any wired connections.
The Sennheiser CX 400BT are passable for phone calls. The integrated mic ensures your voice is clear, although it sounds a bit thin and lacking in detail. It also struggles to separate your voice from moderately noisy environments. These headphones also do an alright job of passively isolating noise around you, but you may have trouble hearing your call if you're surrounded by bass-range noise like bus engines.
- Decent recording quality.
- Disappointing battery performance.
- Bulky design.
Changelog
- Updated Nov 11, 2021: Converted to Test Bench 1.5.
- Updated Jan 04, 2021: We've updated the results of the Equalizer test in App Support.
- Updated Nov 25, 2020: Review published.
- Updated Nov 19, 2020: Early access published.
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Differences Between Sizes And Variants
The Sennheiser CX 400BT come in two color variants: 'Black' and 'White'. We tested the 'Black' variant and you can see its label here. If you come across a variant that's different from our own, let us know in the discussions and we'll update our review.
Popular Headphones Comparisons
The Sennheiser CX 400BT are truly wireless headphones. Although they're very similar to the Sennheiser MOMENTUM True Wireless 2 and have a comparably warm sound profile, they can isolate just as much noise passively without an ANC feature. Their companion app also offers a graphic EQ. However, their battery performance falls a bit short when compared to other truly wireless headphones like the Sony WF-1000XM3 Truly Wireless. Check out our recommendations for the best wireless Bluetooth earbuds, the best true wireless earbuds, and the best earbuds and in-ear headphones.
The Sennheiser CX Plus True Wireless are somewhat better in-ears than the Sennheiser CX 400BT True Wireless. While both are comfortable and well-built, the CX Plus have a slightly better noise isolation performance, a longer continuous battery life, and they have a 'Transparent Hearing' feature, which allows you to better hear your surroundings without turning off your audio. They also support aptX Adaptive codec.
The Sennheiser CX True Wireless are better than the Sennheiser CX 400BT True Wireless for most uses, though the two pairs of headphones are similar overall. The CX have longer battery life and an auto-off timer to help conserve power when not in use. Their companion app also has a slightly wider range of configuration options. Conversely, the CX 400BT offer better microphone recording quality.
The Sennheiser MOMENTUM True Wireless 2 and the Sennheiser CX 400BT True Wireless are very similar headphones, but the CX 400BT are slightly better. While both earbuds are similarly comfortable and well-built, the CX 400BT have a very similar noise isolation performance to the MOMENTUM, even though they don't have an ANC feature. The CX 400BT also have an integrated mic with a better performance.
The Apple AirPods Pro are significantly better headphones than the Sennheiser CX 400BT True Wireless. The Apple are more comfortable, have a better-balanced sound profile, and have a great noise isolation performance thanks to their ANC feature. Their battery performance is better too, and they have an H1 chip so it's easy to pair with different Apple devices. However, the Sennheiser have a better-performing integrated mic, and their companion app offers a lot more customization features.
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