KEF

LSX Stereo Wireless Music System

£1,000 MSRP

I'll be honest, when I first heard there was a big announcement imminent from KEF, I didn't expect a smaller, more compact version of the LS50W. I'd anticipated a larger, floor standing version featuring all that same technology. 

However, it seems KEF has recognised the market trend and shifts towards lifestyle audio products and in this case, found a way to fit all its tech into a smaller box. KEF's LSX is a stereo, compact two-speaker wireless music system.

The famed Uni-Q driver array remains, albeit now a 4.5” version (with integrated 19mm tweeter). The smaller, fabric wrapped curved cabinets house two Class-D amplifiers independently providing the grunt for the drive units, along with a DAC supporting up to 96kHz/24bit when using the master/slave ethernet cable that physically links the two speakers, or 48kHz/24bit if you forego the link cable and pair them wirelessly.

The more compact cabinets which were designed with extensive Finite Element Analysis and employ constrained layer damping (found on higher end KEF speakers) are finished in a choice of five colours. Four choices include cladding in a luxury fabric from Danish textile manufacturer, Kvadrat. Signed by award-winning industrial designer, Michael Young, the fabric options include Black, Blue, Maroon, and Olive. A high gloss White option, sans fabric cladding, is also available.

CONNECTIVITY

KEF has included provision for Spotify Connect, Apple Music, and TIDAL, although, at the time of writing, only TIDAL is available natively through the iOS and Android KEF Stream app. Pre-release, we have been able to use Spotify but only via a Bluetooth (4.2 AptX) connection. 

Just like the welcome news LS50 Wireless owners received, users of Roon please will be pleased to hear that support will be offered with the LSX as a Roon endpoint later.

KEF also tells us an over-the-air firmware update is coming November 1st, 2018 will enable native Spotify along with other improvements, while AirPlay 2 will also become available in January 2019.

KEF's LSX is DLNA compliant, and there's also a TOSLINK (ideal for TV audio connection) as well as a 3.5mm stereo auxiliary input. A subwoofer output is provided, which can be configured from within the KEF Control iOS and Android app. A 5V USB charging output and an Ethernet input round out the rear connections.

Notably absent however is a USB input for connection to a PC or Laptop, which given the compact size of the LSX, seems like a missed opportunity to take advantage of the onboard DAC.

KEF CONTROL AND STREAM

The hub of the KEF LSX system is the KEF Control app. I recall having to jump through quite a few hoops initially to make the necessary connections with the LS50 Wireless. This time around, however, following the prompts to add a new speaker saw the LSX discovered in mere seconds.

On the front of each speaker is an LED with the colour reflecting the input selection which corresponds with the input and colour within the Control app. Curiously, this only applies to the right speaker, with the left speaker’s LED designated only to error display duty. In our time with the LSX, we never saw it light up, which is not necessarily a bad thing, but I suspect this may confuse some users who might think the LED is not working. 

Diving straight into the configuration, you're prompted to enter the parameters for your application. For example, on a desk or stands, the distance to the front of the desk or the rear wall, along with the size of the room and how 'damped' the room is. 

It's worth taking the time to get this right as this all has a significant impact on the sound. This is thanks to KEF's high-tech Music Integrity Engine, which it says is “a cutting-edge collection of bespoke Digital Signal Processing algorithms that ensure accurate time alignment and phase coherence.”

You can also set presets which is handy if you're likely to move the LSX speakers around. And at just 3.6kgs, that's a possibility especially considering that if you opt for a wireless connection, each speaker only needs a connection to power. 

In my case, I created a preset for 'Dining Room' and another for 'Media Room', which are vastly different sized spaces. In one instance I mount them on a timber sideboard, and the other on stands. The Media Room is also extensively acoustically treated, whereas the Dining Room is lively. The Control app allowed for perfect tuning to each space.

From within the Control app, aside from configuration (including options for volume steps, power standby etc.), this is also where you have control over the speakers regarding power status and input selection.

This entire process was straightforward and far more intuitive than I recall when the LS50 Wireless was first released. But it was at this point where my wife wanted the ability to play music as well. 

With both phones now running Control and Stream apps and the LSX paired to Bluetooth (for use with Spotify), there were times where one of us would leave the room and clearly, the other phone would take control. 

Attempting to change tracks or heading back into the Control app, error messages indicated one or both phones had lost control of the LSX speaker. Turning Bluetooth off on one phone, and re-pairing again on the other would resolve the problem, but occasional 'lost control' error messages would continue to appear.

In fairness, our LSX sample is pre-release, and a promised firmware update on November 1st will likely resolve this. In my experience, KEF has always been very quick to respond to bugs and issue over-the-air updates.

With all that aside, once you're ready for music, with just one click, you're sent over to the KEF Stream app.

MAKING MUSIC

With a substantially smaller cabinet (240 x 155 x 180mm), a smaller driver (4.5”, vs 5.25” of the LS50W), and much less power (30w + 70w, vs 30w + 200w of the LS50W) the maximum SPL according to the specifications is 102dB.

For perspective, this is about the same as a jet taking off at 305 meters away or flying over at 1000 feet. It's loud, and prolonged exposure (8+ hours) would cause significant and permanent hearing damage. The point is, KEF's LSX is more than capable of room-filling sound and at typical Hi-Fi levels.

Depending on the DSP settings, the specs also indicate the LSX is capable of a frequency response of 47Hz - 28kHz. In my listening, the bass response was damn impressive from such a small cabinet and just a 4.5” driver!

Of course, you can always add a subwoofer if you do want more bottom end reinforcement. For most users though, you likely won't be left wanting for more.

My listening was predominantly performed via TIDAL from within the Stream app, along with DLNA streaming from my Synology NAS music library.

Since discovering Spanish composer, Alberto Iglesias, 'El Asalto del Hombre Tigre' (The Skin I Live In) is always top of the review playlist. It's a challenging track with pace and dynamics, and it quickly reveals a loudspeaker's ability.

In my highly damped 7.1m x 6.5m room, even at three-quarter volume, the LSX delivered scale and SPL that frankly, surprised me. While the impact of the bass sweeps doesn't carry the weight of a larger sized loudspeaker, what they can do is impressive.

Stereo imagining is tested here with hard panned sound effects and instruments, and the Uni-Q driver used in the LSX is every bit as brilliant as it is in much larger models.

Throughout, even at the limits of the track's wide dynamic range the LSX remains composed and in complete control. 

Australian-American pop/blues singer Nikka Costa released a half-dozen albums through the late 90's and early 2000's. Her first release since 2008 came last year with a selection of covers titled Nikka & Strings. 

The grungy blues rendition of Sinead O'Connor’s 'Nothing Compares 2 U' is fabulous. Another regular highlight on my playlist, the LSX speakers showcased a balanced and beautiful tone on this track, keeping Nikka's powerful, textured vocal rightfully front and centre and in the spotlight.

The soundstage is somewhat narrower and shallower than what I am used to in this room, but that's in comparison to traditional, larger loudspeakers. If viewed with a direct correlation to the physical size of the speakers, then the LSX speakers are projecting a 3-dimensional soundstage that is appropriate.

Don't expect Grateful Dead's 'Wall of Sound' dynamics though. But what you will get is a pair of loudspeakers that gives you an array of connectivity options, sound quality that is unquestionably Hi-Fi grade, and a conveniently small form-factor. 

The sense of scale and ambience found in 'Hey Now' and 'Wasting My Younger Years' from London Grammar's debut album If You Wait is not lost here. In my media room the bass in these tracks was a little shy, but when played in the dining room with some rear loading (and the appropriate DSP preset), it was more balanced.

The star of the show though is the 'tone'. Much like the bigger LS50 Wireless, KEF's active amplification and electronic crossovers, all tuned via digital signal processing, and the seamless transition across the two drivers is in my opinion, spot on. 

I grew up in a house where Jimi Hendrix was only played one way; loud! Not expecting too much, 'Hear My Train a Comin' brought all the grit and overdriven guitar that I'm familiar with to the party. Blues-rock at its finest, and Jimi giving all he had was not lost in this translation some fifty years later. 

From Hendrix to Julia Stone, London Grammar to Rammstein, for what is not much larger than most desktop computer speakers, KEF's LSX have managed to mimic a loudspeaker that is much larger than itself. Remarkably well, in fact.

MUSIC IS MY RELIGION

In the words of Jimi, nothing was more important. More recently, KEF delivered a truly next-generation Hi-Fi product with the LS50 Wireless at a price that anyone with a love for music could justify. Today, the KEF LSX aspires to do the same in a slightly scaled down format, but at an even more affordable price.

Sure, if you're a Hi-Fi enthusiast, you'll get more in many ways with its bigger brother. And while the LSX isn't quite at home in my dedicated room, for me at least, it certainly has a place as a second system in the living area to be enjoyed by the entire family.

The crazed music fans fortunate enough to see Hendrix play Woodstock back in 1969 could not have even imagined this level of audio quality, or the convenience we have available to us today in products such as this.

Raymond Cooke was already revolutionising audio reproduction at KEF back in the 60's, and I'm quite confident he'd be pleased to see his legacy carried on, and the company still pushing the envelope today.

For more information visit KEF.

UPDATE 5th November, 2018: KEF has informed us that an over-the-air firmware v3.0) update is expected in the 3rd or 4th week of November 2018. This update will enable Spotify Connect, Roon, along with various improvements and bug fixes. Users will be notified of the firmware update via the KEF Control app, and will need to connect the ethernet cable between the two speakers and follow the instructions to complete the update.

UPDATE 20th November, 2018: The firmware release (v3.0) has now been rolled out, and enables Roon, Spotify Connect and various improvements and bug fixes. A notification will be sent to users upon opening the KEF Control app.

Related: KEF LSX Compact Stereo Wireless System Unveiled