Sennheiser CX True Wireless Headphones Review

The Sennheiser CX True Wireless are basic-looking in-ears. Their squared-off shape is very similar to the Sennheiser CX 400BT True Wireless, though the newer model features matte-finish touch panels with black embossed logos instead of the older model's glossy touch panels with silver manufacturer logos.

The Sennheiser CX True Wireless are fairly comfortable. They feel lightweight and don't enter your ear canals very deeply. That said, their outer casing protrudes somewhat far from the sides of your head, and they're relatively bulky by the standards of truly wireless headphones.

These headphones have an alright control scheme. It's fairly easy to use for the most part, and you can remap their control scheme through the Sennheiser Smart Control companion app. Tapping on either bud once pauses and plays media or answers and ends phone calls. A double tap on either bud rejects incoming calls, while a triple tap on either bud enables your phone's voice assistant. You can skip to a previous track by double-tapping the left bud. A double tap on the right buds skips to the next track. You can increase or decrease media volume by holding the right or left bud, respectively. The in-ears give you a voice prompt for successful Bluetooth pairing. They also provide an audible chime for each input, and there are different audio cues for increasing or decreasing media volume. Unfortunately, it's easy to accidentally brush their touch panels with your finger when adjusting their fit.

Like most in-ears such as the Cambridge Audio Melomania 1+ True Wireless, these headphones are very breathable. They don't really trap heat inside your ears. Consequently, you shouldn't sweat more than usual if you wear them while working out.

The Sennheiser CX True Wireless are remarkably portable. The buds are very compact and can easily slip into a pocket or a purse. Their case is also very small and should easily fit in most pockets or bags.

The Sennheiser CX True Wireless' charging case is good. It's made of hard plastic, isn't too large, and features magnets inside to keep the buds from falling out of their cradles.

The Sennheiser CX True Wireless feel impressively well-built. They're made entirely from matte-finish hard plastic, which feels sturdy and does a good job resisting fingerprints. Unfortunately, their swappable ear tips feel like they could tear easily. Sennheiser lists an IPX4 rating for water resistance on their website, but we don't currently test for that.

The Sennheiser CX True Wireless are stable in-ears. They don't move around too much with low-intensity movements, though vigorous shakes of the head can loosen their fit.

• Sennheiser CX True Wireless headphones
• 4x Ear tip options
• Charging case
• USB-C to USB-A charging cable
• Safety instruction manual and other guides

The Sennheiser CX True Wireless have a warm, bass-heavy sound profile. This should emphasize the thump and rumble of EDM and hip-hop music but can slightly muddy vocals and lead instruments. Their treble range is also somewhat underemphasized, which can veil the upper harmonics of vocals and lead instruments. Thankfully, their companion app features a graphic EQ and audio presets that let you adjust their audio reproduction to your liking.

These headphones have fantastic frequency response consistency. Once you achieve a proper fit with the included ear tips, bass and treble response should be perceived similarly every time you use them.

The Sennheiser CX True Wireless have decent bass accuracy. The entire range is overemphasized, yielding additional thump and rumble and giving some instruments and vocals extra punch. However, the overemphasized high-bass range can make some mixes boomy and muddy.

These headphones have great mid accuracy. The overemphasis from the bass range carries over into the low-mids, which can muddy vocals and lead instruments. Thankfully, the mid-mid and high-mid ranges are well-balanced and accurate, resulting in clear and present vocals and lead instruments.

These headphones have okay treble response. The low and mid-treble ranges are underemphasized, which can veil vocals and lead instruments and dull sibilants like S and T sounds.

The Sennheiser CX True Wireless have decent peaks and dips performance. A bump in the high-bass range carries over into the low-mids, which gives a muddy quality to some mixes. A dip in the mid-mids can nudge some vocals toward the back of the mix, while a bump in the high-mid range can make them slightly boxy. A larger dip throughout the low-treble range veils vocals and lead instruments. The adjacent rise in the mid-treble range can give a piercing quality to sibilants, like S and T sounds.

These headphones have superb stereo imaging performance. The weighted group delay falls mostly beneath the audibility threshold, resulting in a tight bass and transparent treble response. The L/R drivers are also very well-matched in phase, amplitude, and frequency response, so objects like voices or footsteps should be accurately placed within the stereo image. That said, these results are only valid for our test unit, and yours may perform differently.

Like most closed-back in-ears, the Sennheiser CX True Wireless have a terrible passive soundstage. Creating an out-of-head soundstage relies on interaction with the outer ear, which in-ears like these bypass entirely. Consequently, sound is perceived as coming from inside your head rather than all around you.

The Sennheiser CX True Wireless have a good weighted harmonic distortion performance. Most frequencies fall within good limits, so audio reproduction should be clean and pure.

These are the settings used to test these headphones. Our results are only valid when listening using these settings.

The Sennheiser CX True Wireless have passable noise isolation capability. Unfortunately, unlike the Sennheiser CX Plus True Wireless, they don't have active noise cancelling and rely on their passive noise isolation capabilities to block out ambient noise. That said, they do a bad job of isolating you from bass-range ambient noise, like the rumble of bus and plane engines, but perform very well when it comes to isolating you from mid and treble-range background noise, like chatter from people nearby or the high-pitched hum of an AC unit.

The Sennheiser CX True Wireless have a superb leakage performance. You should be able to listen to content at a high volume without worrying about disturbing people nearby, even in quiet environments.

The integrated mic's recording quality is poor. Recorded speech sounds muffled, thin, and lacking in detail.

The integrated mic delivers decent noise handling capability. People on the other end of the line should understand you fairly clearly if you're calling from a moderately noisy environment, like a busy street. That said, people may have a harder time hearing you if you call from a louder setting, like a moving subway car.

These headphones have satisfactory battery performance. They provide over six and a half hours of playback time on a single charge, which does fall short of the manufacturer's advertised claim of nine hours. Their case should provide roughly two additional charges, which should be sufficient for a couple of days of use. That said, battery life can vary in the real world depending on your usage habits. They're also advertised to supply up to an hour's worth of playback on 15 minutes of charging, but we don't currently test for that. Unlike the older Sennheiser CX 400BT True Wireless, they have an auto-off timer to help conserve the charge when not in use, which you can adjust in their companion app.

The Sennheiser Smart Control app is good. You can customize the headphones' audio reproduction via a graphic EQ or audio presets, which includes the 'Bass Boost' preset for a bit of added thump and rumble, though we don't currently test the headphones with this preset active. You can also re-map their control scheme, turn off audio cues for touch inputs, or check their battery level.

The Sennheiser CX have decent Bluetooth connectivity. They don't support NFC or multi-device pairing, so you can't stream music from your phone while remaining connected to your computer. Their latency on Bluetooth-enabled PCs is high when using SBC or aptX codecs, but they perform very well in this regard when connected to iOS and Android devices, so audio and visuals shouldn't appear out of sync. Of course, it's worth noting that latency can vary drastically depending on the specific device and app that you're using.

The Sennheiser CX are Bluetooth-only headphones and can't be used on a wired connection. They come with a USB-C to USB-A cable for charging their case.

The Sennheiser CX are fully compatible with Bluetooth-enabled PCs. They don't support any other kind of wireless connectivity other than Bluetooth, and their latency is likely to be too high for gaming.

Update 10/27/2021: We incorrectly reported that 'Dock Charging' wasn't supported. However, this was a mistake, and we have changed 'Dock Charging' to 'Yes' and updated our review.

The Sennheiser CX come with a charging case that supplies about two additional charges. You can recharge the case itself via USB-C, but it doesn't support wireless charging.