The Klipsch Flexus Core 300 tops the Flexus Core line of all-in-one soundbars from the American brand in collaboration with Japanese audio stalwarts, Onkyo. The premium 2025 model has extensive wired and wireless connectivity and format support. It's the first model to include a basic version of Dirac Live for room correction, but the full license comes at an extra cost. Speaking of add-ons, while this is a standalone bar, you can make separate purchases of surround speakers and an outboard subwoofer, which seems to put the 'flex' in 'Flexus,' as this is a common thread shared with the step-down Klipsch Flexus Core 200 soundbar.
Our Verdict
The Klipsch Flexus Core 300 is very good for mixed usage. It has comprehensive audio format support covering Dolby Atmos, DTS:X, Dolby Digital Plus, and more, with 2.1-compliant HDMI video passthrough, so you can watch most media without downmixing and use it as an entertainment hub. As a standalone soundbar, it can't quite provide the same rumble and immersiveness available with an outboard sub and rear speakers, but it manages to supply a surprisingly punchy bass. Plus, you have a three-band EQ and EQ presets at your disposal to adjust the tuning to your tastes. The bar includes a basic version of Dirac for room correction, but unfortunately, you need to pay extra for the full license, and the tool tends to reduce the bar's overall output volume.
Extensive audio format compatibility and connectivity.
Plenty of sound enhancements available to adjust the sound.
2.1-class compliant HDMI In.
Premium build quality.
Full version of Dirac Live is behind a paywall.
Bass lacks full rumble and can rattle at high volumes.
Not as loud as advertised.
The Klipsch Core 300 is great for TV shows and dialogue-heavy content. Its discrete center channel sounds pretty natural, so voices sit right in the mix. You can also choose the voice enhancement feature, which has adjustable levels to make speech cut through more, while Night mode means the setting sun doesn't have to limit your viewing. A full selection of EQ presets and a three-band EQ offers you more options for diverse types of TV shows. Besides that, you get comprehensive audio format compatibility, and you can choose between HDMI In, eARC, and Optical connections, so you can watch anything from old DVDs and Blu-ray to the latest big-budget show on streaming.
Extensive audio format compatibility and connectivity.
Plenty of sound enhancements available to adjust the sound.
2.1-class compliant HDMI In.
Premium build quality.
Full version of Dirac Live is behind a paywall.
Bass lacks full rumble and can rattle at high volumes.
Not as loud as advertised.
The Klipsch Flexus Core 300 is very good for music. Its stereo sound is well-tuned with a bevvy of EQ tools available to customize the frequency response and a dedicated 'Music' mode that alters the soundstage. The low-end is punchy, and the mids are fairly even, while the top-end is a little warm. You can use the Dirac room correction tool to meaningfully change the tuning, too, but the full version is an extra cost. The dynamics are good with little compression (although the full version of Dirac seems to compress the sound more while decreasing the max output). Meanwhile, the soundstage is a bit wider than the bar's physical dimensions. The bar is also compatible with all the common wireless platforms like Apple AirPlay and Spotify, so setting the mood is pretty effortless once you've done the setup. Still, for surround sound concerts mixed in 5.1 and Atmos music, it's not as immersive as dedicated rear speakers.
Extensive audio format compatibility and connectivity.
Plenty of sound enhancements available to adjust the sound.
2.1-class compliant HDMI In.
Premium build quality.
Full version of Dirac Live is behind a paywall.
Bass lacks full rumble and can rattle at high volumes.
Not as loud as advertised.
The Klipsch Flexus Core 300 is very good for movies. While its standalone design limits its performance in terms of expansive and immersive 5.1 surround and Dolby Atmos playback, it's well-tuned and does a better job than its form factor suggests. The bar is compatible with most surround and 3D audio formats such as Dolby Digital Plus, DTS, DTS:X, and Dolby Atmos. It also has a room correction tool (though it costs more for the full version of Dirac Live), and you can use the 'Move' listening mode alongside EQ presets or a three-band EQ. Plus, you can manually alter the channel balance, lending you many options to carve out an optimal sound. That said, it's not a very loud soundbar, so if you like your movies loud, you don't get a huge amount of headroom, and while the integrated sub design manages to lend movies a bit of low-end weight, Atmos content lacks rumble. Lastly, stereo Dolby Digital and Dolby Digital Plus audio intentionally play through other speaker channels using phase and delay effects to make a wider sound, but this could bother purists.
Extensive audio format compatibility and connectivity.
Plenty of sound enhancements available to adjust the sound.
2.1-class compliant HDMI In.
Premium build quality.
Full version of Dirac Live is behind a paywall.
Bass lacks full rumble and can rattle at high volumes.
Not as loud as advertised.
Changelog
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Updated Jan 14, 2026:
In the Sound Enhancement Features section of this review, we edited the Rear Level Adjustment toggle to No, since to toggle rear level, you need to purchase extra speakers that are not included with this package.
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Updated Oct 24, 2025:
We added a reference to the KEF XIO in the Audio Latency: ARC box.
- Updated Sep 18, 2025: Review published.
- Updated Sep 10, 2025: Early access published.
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Differences Between Sizes And Variants
The Klipsch Flexus Core 300 comes in 'Black' or a 'Walnut Vinyl' colorway (which is shown on the Klipsch site, but actual availability seems scant). You can view our 'Black' unit's label. The soundbar is also called the XCORE300 in some regions. Our review is only valid for the all-in-one model, but you can purchase additional rear speakers and a subwoofer, including the Klipsch Flexus Surr 200 and Klipsch Flexus Sub 200, which will change the sound performance measurements.
If you come across another variant of this soundbar, let us know in the comments, and we'll add it to the review.
Popular Soundbar Comparisons
The Klipsch Flexus Core 300 belongs to the same line as the lower-tiered Klipsch Flexus Core 200, and the upgraded model adds room correction, better connectivity, and greater audio format support, though they're both well-made bars that you can add more speakers to. Despite being an all-in-one design, the Flexus Core 300 includes an integrated subwoofer, similar to the Sonos Arc Ultra, for a 5.1.2 configuration. The Flexus Core 300's impressive selling points include the full audio format support and connectivity that beats out the Sonos, but without the Sonos' large ecosystem. On the other hand, when considering a premium-tier soundbar, if space isn't a limitation, you might prefer a soundbar with a dedicated sub and rear satellites for improved low-end rumble and more enveloping sound, like the Samsung HW-Q910D.
For more recommendations, check out the best all-in-one soundbars, the best Dolby Atmos soundbars, and the best 5.1 soundbars.
The Sonos Arc Ultra and the Klipsch Flexus Core 300 are both premium 5.1.2 soundbars that you can expand with additional speakers. With the Sonos, you get the benefits of a large ecosystem of other products, a pretty simple setup, and a slightly louder and less compressed sound. And while Atmos isn't as evenly tuned on the Sonos, it sits louder in the mix. On the other hand, the Klipsch outperforms the Sonos concerning connectivity and audio format support, making it a much more flexible standalone bar that you can use as an entertainment hub and for gaming. Plus, it has a deeper low-frequency extension for a touch more bass.
The Klipsch Flexus Core 300 is a slightly better all-in-one 5.1.2 soundbar than the Sennheiser AMBEO Soundbar Plus. While both bars have built-in subs and let you add a wired outboard sub too, the Klipsch has a more powerful bassy punch. Even though these soundbars support similar audio format selections and have HDMI In ports, the Klipsch possesses a more up-to-date 2.1 class-compliant spec, which is great for sports and gaming. It also has a more even Atmos and surround sound tuning. Still, the Sennheiser is more compact, boasts an extra HDMI In port, and despite its smaller size, has a neutral tuning, a similar soundstage width, a slightly louder max volume, and a bit less compression at max.
The 5.1.2 Klipsch Flexus Core 300 is an upgrade over the 3.1.2 Klipsch Flexus Core 200. The Flexus Core 300 includes greater audio format support, such as DTS and DTS:X. You also get room correction and more wireless playback options with the Flexus Core 300. Still, both bars have limitations around how impressive surround sound and Atmos can be in a standalone bar. If you mostly watch dialogue-heavy TV or listen to stereo music mixes, the Flexus Core 200 may suffice, as it still boasts a solid tuning and the leeway of EQ presets to play with the sound. That said, it's a much more limited soundbar that downmixes surround audio to stereo.
The Klipsch Flexus Core 300 is a better all-in-one soundbar than the KEF XIO, with a couple of caveats. The Klipsch is able to put out more low-end rumble, which techno and action movie fans alike will appreciate. It also offers more sound enhancement features, including a room correction option, and a full graphic EQ and presets, where the KEF sticks to bass and treble controls. The KEF does pull ahead in a couple of places, though. First, it offers more immersive Atmos performance. Second, it has lower latency, although you're limited to eARC and Optical, where the Klipsch has a full HDMI In port, too.
Test Results
