KEF XIO

Introduction

A KEF spatial audio soundbar seems to have been a long time coming, but no one can accuse the company of not making a splash now it has finally delivered the goods.

In every respect – specification, physical size, price – the XIO is a statement product. But just how sweet a statement is it?

Design

• 70 x 1210 x 170mm (HWD)
• Choice of two finishes
• Weighs 10.5kg

It’s the bar part of the word soundbar that tends to dictate the design of most products like this – and although the KEF XIO has one or two mildly interesting touches, fundamentally it’s soundbar business as usual here.

The XIO is designed to work in one of two orientations: on-shelf or on-wall. On the shelf it’s 70 x 1210 x 170mm (HWD) – which is usefully low-profile when it comes to staying clear of the bottom of a TV screen.

On the wall it becomes 170 x 1210 x 170mm (HWD) – and in this orientation the driver behind the acoustic cloth in the centre of the front surface becomes live. No matter where you put it, though, an all-in weight of 10.5kg shouldn’t be problematic.

The choice of finishes (black or grey, the latter of which KEF insists is silver) help to minimise the relative bulk – although the XIO is nevertheless going to look a bit daft accompanying a TV any smaller than 55-inches or so. The combination of acoustic cloth and aluminum both looks and feels good, and the standard of build and finish is pretty much impeccable.

Control is available via the surface of the XIO, a remote control handset and the KEF Connect app that’s free for iOS and Android. A few touch-controls on the top-plate grant access to volume up/down/mute (with a little row of LEDs letting you know how much volume you’re getting), input selection and power on/off.

The remote control handset feels quite good in the hand, and as well as duplicating these functions it offers access to a couple of EQ presets and the basic playback controls of play/pause, skip forwards and skip backwards. It’s far from responsive, though, and the lag between pressing a button and getting what you want can be quite frustrating.

Features

• 5.1.2 channels of sound from 12 drivers
• Dolby Atmos, DTS:X and Sony 360 Reality Audio compatibility
• No HDMI pass-through

As the asking price demands, the KEF XIO uses an array of physical drive units, rather than digital sound processing, to create the sensation of spatial audio. And as the asking price also demands, it’s thoroughly specified to do so in some style.

At either end of the soundbar there is a 50mm full-range dynamic driver, angled out to create some sonic width. Across the front (when in shelf orientation) there are three UniQ MX drivers that are a variation on the established KEF UniQ theme, and another three are arranged across the top surface.

Only two of these are operational when the soundbar is on a shelf, the third (behind that circle of acoustic cloth in the centre of the surface) comes into play when the XIO is wall-mounted. Configured this way, of course, three UniQ MX face forwards, three fire upwards.

Unlike the usual UniQ driver, which features two separate drive units (mid/bass and tweeter) positioned coaxially in a single assembly, the MX variation has a mechanical crossover that allows each part of the dual-diaphragm layout to operate independently of each other. 

Finally, there is a quartet of P185 low-frequency drivers, arranged in two back-to-back pairs – this layout is intended to offer worthwhile force-cancellation and to keep unwanted internal vibrations to a minimum.

Each 51 x 180mm racetrack driver features KEF’s P-Flex technology (the carefully designed surround first seen on the KC series of subwoofers that allows significant driver excursion) – KEF reckons this lets each driver deliver the same sort of bass presence as a more traditional drive unit of 10cm diameter.

That’s a 12-driver line-up, and so obviously the XIO is equipped with 12 discrete blocks of Class D amplification. KEF reckons it’s a set-up that can twist out 820 watts of peak power – which really should be ample to deal with even the biggest dynamic upheavals in a soundtrack.

Of course, KEF hasn’t just amplified some carefully positioned drive units and left it at that. Intelligent Placement Technology (IPT) acts as a calibration tool that lets the XIO use its integrated mics to optimise its output to best suit the environment in which you’ve placed it.

Velocity Control Technology (VECO) monitors the P185 drivers and creates a negative feedback loop in opposition to their activity in an effort to further minimise distortion. And a ‘for cinema’ version of KEF’s Music Integrity Engine (MIE) offers a number of digital sound-processing algorithms with multi-channel processing, adaptive placement and virtualisation abilities – and these are in addition to a selection of app-stored EQ settings like Night, Music, Movie, Direct and so on.

Where spatial audio compatibility is concerned, the XIO covers the waterfront. It’s comfortable with Dolby Atmos, DTS:X and Sony 360 Reality Audio. On top of this, the app has support for Amazon Music, Deezer, Qobuz, and the ‘Connect’ versions of Spotify and TIDAL.

Wireless connectivity is dealt with by Bluetooth 5.3 and, of course, dual-band wi-fi which allows for AirPlay, Google Cast and UPnP compatibility. Physical inputs, meanwhile, run to a USB socket, digital optical input and a single HDMI 2.1 eARC. This is the only area of the XIO’s specification that seems inadequate, and it’s significant for more than box-ticking reasons.

An HDMI pass-through would seem a minimum requirement for a soundbar costing very nearly £2K – every other soundbar with aspirations towards ‘premium’ features an HDMI pass-through, and for good reason. It’s an oversight, no two ways about it.

KEF Connect is stable, in-depth and logical, and will assist with everything from initial calibration to custom EQ settings and accessing the KEF’s numerous DSP settings. You can’t control playback when the soundbar is playing via HDMI, sadly, but otherwise it has everything you want.

Sound Quality

• Open, detailed and carefully organised sound
• Frankly unlikely bass presence and heft
• Very adept when it comes to music too

I might as well get right to it: the KEF XIO is the best-sounding, most convincing spatial audio soundbar currently available. Perhaps you’re tempted to say “just as it should be” when you remind yourself of the asking price – but KEF wouldn’t be the first company to have launched an expensive product that doesn’t have the performance to back it up. The XIO, though, needs no excuses made for it.

With Hans Zimmer’s exemplary soundtrack to Dune playing via 4K Blu-ray disc, the XIO creates a soundstage that’s controlled, spacious and brilliantly resolved in every direction. There’s width, depth and, yes, height to the sound, and when movement occurs it’s steered through the dome of sound with complete positivity.

No soundbar is ever going to fool you into thinking there are speakers directly above you, but the KEF is the most immersive and enveloping spatial audio soundbar I’ve heard. And I’m fairly sure I’ve heard almost all of them.

Detail levels are sky-high, there’s proper bite and rasp to high frequencies and the midrange communicates with a sort of direct eloquence that means even hissed or whispered dialogue projects properly.

Bass response, meanwhile, is approaching prodigious: the XIO summons remarkable low-frequency presence and solidity, hits with implacable authority and controls the attack and decay of low-end sounds with an iron fist. There’s a stack of variation to the bottom end here, too – the KEF is no mindless thumper (even when describing the sound of the movie’s thumpers).

Integration between these numerous drivers is smooth, and once the soundbar has calibrated itself to the specifics of your room there’s no sense that any part of the frequency range is being understated or oversold.

There’s more than enough dynamic headroom available to make Zimmer’s sudden and considerable shifts in intensity and straight-ahead volume perfectly apparent – that claim for over 800 watts of peak power seems reasonable enough. And the more subtle dynamic variations in voices or sound effects, the harmonic over- and undertones, are identified and given their due prominence. There’s so much space available on the XIO’s soundstage that even the most complex scenes are open and easy to follow.

Switch to the Dolby Atmos mix of Lorde’s Virgin and the story is much the same – which makes the KEF an excellent speaker for music in general and among the most musical soundbars around.

Everything that’s admirable about the movie performance – frequency response, low-end fidelity, detail retrieval, dynamic heft, clarity of soundstage, you name it – is carried over intact. The amount of space available on the stage is remarkable – and yet the music is presented with unity and quite tight togetherness.

Ordinarily a soundbar is often only useful as an occasional music speaker, but the XIO could quite easily be the only speaker you need in your TV room. Which (and join in if you know the words) is “just as it should be”.

Should you buy it?

FAQs