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Sennheiser CX Plus True Wireless Earphones: Review

The Sennheiser CX Plus wireless earbuds add Active Noise Cancellation and aptX Adaptive Bluetooth to the regular CX earphones.

Sennheiser CX Plus True Wireless Earphones in front of charging case black

I recently reviewed the Sennheiser CX and suggested that the CX was a viable alternative to the Apple Airpods. With the next generation Apple AirPods 3 just announced on Monday, that comparison becomes more interesting and it is one that we plan on doing before the end of 2021. One thing I noted was that if you wanted active noise cancelling, you’d need to step up to the considerably more expensive Momentum TWS. I’d love to think that the Sennheiser CX Plus were in response to my prose, but this new pair of true wireless earphones have been in the works for awhile.

Apple delayed the release of the AirPods 3 by almost 8 months and that created an opportunity for Sennheiser, Sony, Bose, and Master & Dynamic to get their next generation products into the market.

The other piece of good news is those who don’t need ANC can get the CX for $50 less ($129 USD), although we’ve also seen it on sale for as low as $99.

But let’s get back to the Sennheiser CX Plus which I’ve had for a few weeks.

Sennheiser CX Plus True Wireless Earbud Pair Facing Up
Sennheiser CX Plus

The new Sennheiser CX Plus is basically a CX with an upgraded Bluetooth module and active noise cancelling added. The driver remains unchanged; which is a good thing since I found the tonality of the CX to be among the best in its class and definitely superior to the current Apple Airpods.   

The upgrade to the Bluetooth module adds aptX Adaptive to the list of supported protocols which is a big step up from the CX which only supported aptX, AAC, and SBC.

Sennheiser CX Plus True Wireless Earphones in front of charging case

This feature alone may be enough to justify the difference in cost as aptX Adaptive incorporates low latency technology along with an adaptive bit rate that allows the codec to make the best use of bandwidth available unlike most other protocols that use a single on a handful of pre-determined bit rates.    

Right now it is arguable as to which is better aptX Adaptive or LDAC, but both are a vast improvement over earlier versions of the Bluetooth protocols and with aptX Adaptive being native to most Qualcomm chipsets, it has a broader reach than the Sony licensed LDAC codec.

Sennheiser CX Plus Wireless Earbud Side No Tip

The recent announcement in regard to Bluetooth aptX Lossless is certainly something to look forward to but it will be another 4-5 months before we see any true wireless products for sale utilizing this new technology. The chip shortage may also delay those introductions so it’s something to pay attention to.

The big selling point of the Sennheiser CX Plus though is the combination of active noise cancelling and ambient listening; what Sennheiser calls “Transparent Hearing.”

Sennheiser CX Plus Wireless Earbud Back

The new CX Plus uses the microphones in the original CX; it has the ability to use the microphone to let in a little or a lot of the surrounding sounds so the user can maintain situational awareness, or it can use that same data to actively block outside noise.

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The CX Plus also allows for sidetones so the user can adjust how much of their own voice they hear in phone calls.

To use these new features most effectively, one needs the Sennheiser app installed on their smartphone or tablet. The very first time you pair the earphones to your wireless device, the app will notify you that new firmware exists. I found this interesting because I had one of the first review samples and the CX Plus had only been available for 2 weeks.

The first firmware update listed an update to the aforementioned “Transparent Hearing” system and I suspect it’s something that you need to do as soon as time permits. The update took a surprisingly long 15 minutes using my Samsung S20 and high speed internet service.

Sennheiser CX Plus Wireless Earbud Bottom

Sorry I Can’t Hear You

I found the app a little clunky in that the settings for transparent audio are on the main page, but the setting for ANC is under the settings sub-menu and requires you click the gear at top right to find it.   

Once you sort out the controls, the ANC works well as does the transparent hearing setting, although I did find that the transparent hearing required that the music volume be kept fairly low in order not to drown out the ambient noise.  

There is an option to pause music when external voices are present and I would recommend that for those who have a critical need to hear external noise as it was possible to lose some of the ambient noise even at normal listening levels with the pause feature disabled.

Battery life is impacted by ANC and transparent hearing but it still lasted over 7 hours for me, so a normal business day should be quite possible even with ANC enabled and the case still offers two full charges for the earpieces; a quick 30 minute break during the day would allow enough of a recharge to make it 12-15 hours between full charge cycles.    

The drivers are the same Sennheiser 7mm “True Response Transducer” dynamic driver which are the heart of most of their IEM’s including the newly released IE300 and IE900.   

Sennheiser CX Plus Earbud Internals

Sound Quality

The CX Plus and CX sound nearly identical when ANC and Transparent Hearing are disabled. Both start with an emphasized sub-bass that gradually drops back as it moves through the mid-bass and lower midrange. 

The midrange is mildly recessed as is the lower treble before the true treble picks back up again and completes the V. Roll-off is fairly steep above about 12kHz which does limit air and sparkle slightly but not enough to make the CX models sound closed in. 

Both CX twins have good detail throughout and even with the strong low end response, texture is never smeared listening to any genre of music.

With ANC enabled, there is a drop in sound quality; something that is commonplace with all ANC models but it isn’t as intrusive as with some of its competitors. Neither CX model have the audible hiss that is commonly heard with budget ANC models.  

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Sennheiser CX Plus True Wireless Earbud Kit

It is important to note that this model has already seen at least two firmware updates since it was released as they continue to tweak the ANC sub-systems, so I have reason to believe Sennheiser will continue to work to improve the CX Plus in the coming months.


I had originally recommended the CX as a worthy alternative to the Apple Airpods at a better price; with the $30 drop in price they are an even better value. Likewise, the CX Plus is a solid alternative to the AIrPod Pro and at $179 leaves a bit more change in your pocket in the process. The brand new AirPods (3rd generation) are the same price which makes a natural rival, except AirPods 3 do not have ANC.

Both Sennheiser CX models would make great stocking stuffers for the music lover on your holiday shopping list and with Sennheiser’s warranty, they should last well after the holiday season has passed.


For more information: Sennheiser CX Plus

Where to buy: $179 at Amazon | Crutchfield

Read next: Best True Wireless Earbuds Right Now

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