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KEF X300A review

KEF X300 A review speakers angle
MSRP $799.00
“Let’s not beat around the bush: The KEF X300As are one of the most thrillingly enjoyable speaker systems we’ve heard in quite some time.”
  • Class-leading, audiophile-grade sonics
  • Exciting, lively tonal balance with excellent detail
  • Sound great in a variety of locations
  • Wide dispersion design easily fills a room
  • Awesome build quality
  • Lively balance occasionally tends towards brightness
  • Mildly finicky about placement
  • DAC resolution somewhat limited

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When it comes to high-tech engineering and high-quality sound, few speaker companies can match KEF’s endeavors. The British-based, Asian-owned company has been designing advanced drivers for over 50 years, both for its own speakers and for numerous other companies.

… nothing prepared us for just how attractive their textured, gun metal-colored enclosures look in person…

Perhaps KEF is best known these days for its Uni-Q design, a midrange/woofer unit with a concentrically-mounted tweeter placed at the driver’s acoustic center, creating a virtual point-source transducer. The driver design was distinctive enough for KEF to earn a patent on it in 1989, and the Uni-Q technology is now featured across most of the company’s speaker systems.

Little surprise then that a pair of those Uni-Q drivers should anchor the X300A, KEF’s first self-powered, digital input speaker system. At first blush, it’s easy to think of this system as nothing more than a pair of super-fancy computer speakers; its $799 price tag certainly doesn’t help that image, either. Thank goodness, then, that KEF’s history of offering superb value holds doubly true in this case, making the X300As one of KEF’s best designs yet. Read on for our detailed findings.

Out of the Box

“Impressively good-looking.” That’s what we initially thought when we first unboxed the KEF X300As. Even though we’d seen countless pictures of these speakers on the interwebs, nothing prepared us for just how attractive their textured, gun metal-colored enclosures look in person, especially when set off by the smooth, satin-finished, darker-shaded front baffle and metallic-hued driver. We think the X300A’s thoroughly modern look complements its equally modern technology and should fit nicely into a wide variety of decors.

Pulling the X300As from their shipping carton, we were surprised by how heavy these speakers are. With fairly compact dimensions of 11.1 x 7.1 x 9.6 inches, each holding in 16.5 lbs. worth of powered speaker goodness, it’s no wonder these KEFs feel as solidly hefty and inert as they do. No doubt the substantial, machined aluminum heat sinks protruding from the enclosures’ backsides also help explain a good chunk of the weight.

KEF X300 A review speaker
Image used with permission by copyright holder

Once we closely examined those gorgeous metal drivers, we saw just how well-built the X300A’s Uni-Q drivers really are. Everything from the unique ribbed, “Z-Flex” surrounds, to the tweeter’s waveguide assembly, to the ultra-tight woofer and tweeter tolerances, speaks to the high manufacturing quality and care KEF pours into these speakers. It’s enough to make some much more boutique rival speaker companies’ systems completely jealous.

Other items found inside the box include a pair of two-piece port plugs, a mini-to-standard USB input cable, USB connection cable, rubber footer pads, power cords, and a quick start guide and warranty card.


The KEF X300As essentially combine the company’s more traditionally-configured passive Q100 speakers with on-board amplification and D/A converters. The result is a self-contained music system requiring only a source component to operate. The speakers connect directly to your PC or Mac, desktop or laptop computer’s USB port via its mini-USB input located on the left speaker; the right channel signal is then routed digitally from the left speaker’s USB output to a similar input on the right-channel speaker’s rear panel.

… the KEF X300A will reward you with some of the most stable, coherent, and realistic imaging you’ll get from any speaker, at any price.

The X300A’s USB input operates in asynchronous mode, which means it will bypass your computer’s low-grade, internal D/A converter for a pure digital signal transfer. This approach makes the best use of the X300A’s own internal twin DACs (one for each speaker) and should result in noticeably better sound than what’s otherwise available from your computer’s own converters.

Curiously, the X300A’s DACs can process signals up to a 24-bit, 96 kHz resolution, but no higher. Given these speakers’ premium positioning and their targeted customer, we have to wonder why KEF didn’t make the X300As compatible with higher sampling rates, such as 176.4 or 192 kHz. Nevertheless, their resolution capability is nothing to scoff at, and in real world terms, it’s much higher in bandwidth than the majority of music files most consumers are listening to anyway.

The KEF X300As sport one of the company’s latest aluminum/magnesium hybrid, 5.25-inch Uni-Q drivers; the concentrically-mounted, vented 1-inch dome tweeters are made without the magnesium. Those tweeters are also fitted with KEF’s “Tangerine Waveguide” assembly, said to reduce sweet-spotting effects while increasing both dispersion capabilities and placement flexibility.

Instead of going the easy route with the typical pre-fab, class D amp modules, KEF chose to design and manufacture its own class A/B amplifiers for the X300a for sound quality reasons. In fact, each enclosure houses its own pair of amplifiers capable of delivering 50 watts of power to the woofer and 20 watts to the tweeter. Those amplifiers use high-quality toroidal transformers in the power supplies, relying on the aforementioned heat sinks to maintain optimum operating temperatures.

Another nice feature of the X300As is the rear panel, 3.5 mm analog input on the left speaker. This affords direct connection to your smartphone, tablet, or other source component with analog audio outputs. Note however that this signal runs through the speakers’ own A/D and D/A converters, which means the KEFs aren’t capable of a pure analog signal path. And while there’s no built-in option for streaming audio, KEF does throw in a $99 AirPlay dongle for free upon registration.

Lastly, the KEF X300As include both volume and balance controls and a two-position EQ switch to tailor the speakers’ response for either desktop or free-air use; a pair of two-piece port plugs also help contour the speaker’s bass response depending on speaker placement.

Set Up

Since the X300As are so flexible when it comes to placement, we tried them in a wide variety of locations, including on top of our A/V stand, on a desktop, in the nearfield at our workstation, and in a free air setup which we ended up using for most of our listening. The KEFs consistently sounded good in all of these positions and were especially fine in the A/V stand and desktop locations.

But when we first positioned them on dedicated stands out into the room, the treble sounded much too bright. Once we carefully tweaked their positions however, the X300As sounded absolutely awesome out in the open. Nearly all of the excess brightness was gone, putting all of the KEF’s positive traits back on display.

We spent more time listening and tweaking until we were happy with the sound. We settled on placing the speakers on a pair of 28” BTech Apollo speaker stands 6’ apart with the front baffles 17 inches from the wall behind them. This placement proved ideal in both our small 11’ x 14’ room and our larger 14’ x 24’ living room. Bottom line: Spend some time fine-tuning the X300As’ positioning to coax out all of the sound quality they’re capable of.


Since the X300A’s input options are limited by design, testing them with a wide variety of gear isn’t an option; you must connect these speakers via a USB 2.0 (or higher) port to your computer, laptop, or other direct digital output to get the most out of them. We therefore did the majority of our testing with our HP Pavilion G6-2320DX laptop running Media Monkey software, version, for FLAC and WAV files. We also used Apple iTunes version for AIFF files.

We also did some evaluations with our Apple iPhone 4 and a 2nd generation Apple iPod Shuffle connected to the analog input to see how these would fare. Note however that since the analog input digitizes all incoming signals, trying to make meaningful comparisons between the X300A’s own internal DACs and other manufacturer’s external ones aren’t possible.

KEF X300 A review speaker macro
Image used with permission by copyright holder

After we dialed-in their positions, we let the X300As break in for what seemed like an eternity before we did any serious listening. We must’ve played at least 50 hours worth of music before they really opened up and came into their own. Once that was finished, the X300A’s sounded noticeably better: Bass was richer, the midrange lost its shoutiness, and the treble sounded much smoother and more finely detailed.

Thankfully, listening to these speakers post break-in was definitely worth the wait. Spinning up “This Charming Man” from the Smiths’ Complete collection, we were instantly smitten with the KEF X300As’ thrillingly brilliant and lively tonal balance. Their exciting and up-front presentation had us bobbin’ our head and tappin’ our toes more than any other similarly-priced speaker in recent memory, self-powered or not.

We proceeded listening to countless different albums over the next several weeks, and regardless of musical genre, the KEF’s always sounded clear, open and highly detailed without ever being aggressively so. What’s more, these “computer speakers” have a refreshing transparency and directness that’s often missing from more typical audiophile-approved speakers, making much of the competition sound distorted and veiled by comparison.

… each enclosure houses its own pair of amplifiers capable of delivering 50 watts of power to the woofer and 20 watts to the tweeter.

Consequently, the KEFs are a champ at conveying sonic details that make high-quality recordings shine. Listening to a 24-bit/96 kHz rip of Beck’s seminal break-up album Sea Change, we marveled at how the warm bass and lush vocals were engineered to provide an up-close and intimate vibe. It was also easy to hear how much harmonic decay and transient information contribute to the overall aural soundscape of this fine recording.

Keep in mind though that the X300As’ insight into a recording’s fidelity can go the other way, too. Give them a dog of a recording, such as Justin Timberlake’s musically excellent but sonically lackluster The 20/20 Experience, and you’ll clearly make out how all of the instruments sound electronically processed, stripped of harmonic content and devoid of transients, much like a low-bit rate MP3. Thankfully, the KEF X300As pull off the neat trick of sounding revealing without ever being ruthlessly so, making it easy to enjoy even the worst recording in your collection.

Of course, it’s this revealing quality that brings out all of the detail hidden in the music as well. This was plainly evident while listening to the track “Wagon Wheels,” from Joshua Redman’s future classic Back East. Here, Ruben Roger’s bass sounded wonderfully nimble, surprisingly weighty, and cleanly articulate, and Redman’s sax had a lifelike roundness to its tone while still sounding appropriately sharp and blatty when called for.

Perhaps best of all though is these speakers’ uncanny way with the pace, rhythm and timing of the music at hand. The KEF X300As are one of the few reasonably-priced speakers we’ve heard that sounds naturally propulsive regardless of musical genre.

Listening to Ry Cooder and Ali Farka Toure’s wonderful collaboration, Talking Timbuktu, we couldn’t get over how deftly the KEFs delivered all of the intricate rhythmic details interwoven throughout each track on this album. Every note’s attack, sustain, and decay components came through effortlessly, and percussion instruments in particular had an excellent tactility that allowed you to hear hands hitting drum skins in the same plumby, resonating way they do in real life.

But no speaker is perfect, including the X300A. While they’re about as close to perfection as you can get for the price, they do have a couple of flaws, however minor they may be. Given the right recording, such as Hilary Hahn’s wonderful Bach Concertos, their lively balance can turn into a bit of treble brightness, even with optimized speaker positioning. Thankfully, this brightness is never objectionable; it’s simply “there.” This can quickly turn into a persistent stridency though if the speakers are haphazardly placed about the room.

KEF X300 A review speaker bottom macro
Image used with permission by copyright holder

Which leads us to these speakers’ other teensy-weensy drawback: The X300As can be finicky about setup and placement. Given that they sound so good in a wide variety of locations, we were a little surprised by this discovery. Perhaps we shouldn’t have been, however: Considering these speakers’ wide and even dispersion, they had no trouble filling up both of our listening rooms with clear, crystalline sound. Consequently, it’s easy to see how the X300As’ may be more influenced by room acoustics than other, more directional designs.

But spend a little extra time getting their placement dialed in, and the KEF X300As will reward you with some of the most stable, coherent, and realistic imaging you’ll get from any speaker, at any price. The soundstage is deep, wide and precise in all dimensions, and we could clearly pick out individual performers within intricately layered recordings, such as Stile Antico’s sublime massed choral album, Music for Compline.


Let’s not beat around the bush: The KEF X300As are one of the most thrillingly enjoyable speaker systems we’ve heard in quite some time. Its combination of class-leading transparency, lively and detailed tonal balance, placement versatility, and room-filling capabilities really had us over the moon. Add in their wonderful aesthetics, ease of use and self-contained design, and it becomes damn near impossible to think of anyone who wouldn’t enjoy these KEFs.

Sure, we could be hyper critical and go back to the system’s treble brightness and placement sensitivities, but doing so would miss the point entirely: the X300As make it super easy for anyone, make that everyone, to enjoy jaw-droppingly good, audiophile-quality computer sound in the simplest and most direct way possible.

Major, major kudos to KEF then for making the best “computer speakers” this reviewer’s heard yet. If you’re interested in exploring your own path computer audio nirvana, the KEF X300As should be the first stop on your digital musical journey.


  • Class-leading, audiophile-grade sonics
  • Exciting, lively tonal balance with excellent detail
  • Sound great in a variety of locations
  • Wide dispersion design easily fills a room
  • Awesome build quality


  • Lively balance occasionally tends towards brightness
  • Mildly finicky about placement
  • DAC resolution somewhat limited

Editors' Recommendations

Oliver Amnuayphol
Oliver Amnuayphol is a Hi-Fi, home theater and sound geek who did time as an audio guru, blogger, A/V sales associate, and…
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