Sennheiser CX 400BT True Wireless Review: Bulky but bold

The first thing you'll notice about the Sennheiser CX 400BT True Wireless headphones is just how large the charging case is. It's roughly what you'd get if you stuck two AirPods Pro cases together. You're never going to forget you've got it in pocket. In short, it's a real chonky lad.

The second thing is the size and shape of the buds. The CX 400 BTs are best described as rather thick squovals that can't help but protrude from your ear. While they don't have a stemmed design like AirPods, the CX 400 BTs are arguably less subtle due to their sheer magnitude.

Despite this, the buds are actually pretty comfortable - even with extended listening - and they're lighter than you'd expect. There's no IP rating, however; you don't even get splash resistance. I didn't have any issues wearing the CX 400BTs at the gym, but they may not be the best choice if you're after workout earbuds.

Where the CX 400BTs really shine is audio quality. They're clear, detailed headphones that should admirably handle whatever you throw at them. Low-end frequencies have a welcome presence in the mix, but never feel overwhelming or like they're making the rest of the track sound muddy. Mids and trebles are both equally present and clear. The CX 400BTs also do an excellent job at portraying deep sub-bass. This is topped off with plenty of dynamic range that helps showcase subtler elements in a song and convey the full depth of a recording. All in all, the CX 400 BTs sound pretty damn good.

The CX 400BTs also do a great job when it comes to battery. You'll get almost seven hours of playback before you need to recharge the buds. When combined with the case, you'll get as much as 20 hours. Seven hours is great for a pair of wire-free headphones, which often average around five. It would have been nice to see the case offer a bit more juice, given the sheer size, however.

One key omission from the CX 400BTs is active noise-cancelling, which we've started to see in other devices around the $299 price-point, such as the OPPO Enco W51s. The in-ear fit means they'll block out a little bit of noise, but I could still hear myself typing over music when using the CX 400BTs.

At their full retail price of $299, the Sennheiser CX 400BTs are a little hard to recommend. You're better off spending just a little extra on the Samsung Galaxy Buds Pro to get noise cancelling, an IP-rating, and a more refined design. However, if you can find them on the cheap, Sennheiser CX 400BTs are much easier to recommend. They sound excellent, the battery lasts for ages, and they're pretty comfortable - even if they do look bulky. We've seen them drop as low as $150, at which point they're a bargain.

Alex Choros

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Alex Choros is the Managing Editor of WhistleOut Australia and an award-winning journalist. He's been writing about consumer technology for over a decade and is an expert on the Australian telco sector, to the point where he knows far too many phone and internet plans by heart. In addition to leading the WhistleOut editorial team, Alex is responsible for ruining the office Sonos with his troubled taste in music.

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