Founded in 1961, KEF is a well-known, high-end British speaker brand with many outstanding products to its credit. These days, small wireless speakers are all the rage, and KEF has embraced that market with several models, including the new LSX. Let’s see if it’s worthy of KEF’s legacy.

The KEF LSX is relatively small, measuring 9.5 x 6.1 x 7.1 inches (H x W x D), but it feels quite substantial (weighing just under eight pounds). To match almost any decor, it’s available in five colors: black, green, blue, red, and gloss white. In each case (except white), the sides, top, and bottom are wrapped in a color-matched fabric from Danish textile designer Kvadrat.

A gently convex front baffle helps minimize diffraction of sounds from the driver. Speaking of which, the driver is a KEF-developed Uni-Q coaxial design. A 0.75-inch aluminum-dome tweeter is located at the center of a 4.5-inch magnesium/aluminum alloy-cone midrange/woofer. This configuration is intended to make sounds from both transducers radiate from the same point and improve stereo imaging.

kef lsx uni qKEF
The KEF Uni-Q driver consists of a 0.75-inch aluminum-dome tweeter located at the center of a 4.5-inch magnesium/aluminum alloy-cone midrange/woofer.

The Uni-Q driver is powered by amplifiers providing 70 watts for the midrange/woofer and 30W for the tweeter. KEF specifies a frequency range (-6 dB) up to 47kHz; the low end of that range depends on the Bass Extension setting in the KEF Control app: 49-, 52-, or 55Hz. By contrast, the frequency response (±3 dB) is specified up to 28kHz and down to 54-, 59-, or 69Hz, depending on the Bass Extension setting. The low end is enhanced by a port on the back of the speaker as well as KEF’s Music Integrity Engine digital signal processing. The maximum output is spec’d at 102dB SPL.

As a wireless speaker, the LSX accepts audio via Bluetooth 4.2 (with support for the aptX codec), and it will remember up to eight Bluetooth devices. It will also support Apple AirPlay 2 in a soon-to-be-released firmware update. In addition, it can stream music from online providers Tidal and Spotify as well as local NAS drives or computers via DLNA over your home’s Wi-Fi network (2.4- or 5GHz, 802.11a/b/g/n).

The LSX supports digital-audio streams with resolutions up to 192kHz/24-bit. Ethernet connections, however, max out at 96/24, and wireless connections are limited to 48/24, so anything higher is downsampled as needed.

kef lsx connectionsKEF
A nice complement of connections. Notice the AC power receptacle; it’s an IEC standard configuration, but not the one I would have wished for.

This speaker is sold in pairs; one is called the Master and the other is called the Slave. The Master provides all the connections on its back panel, including a TOSlink optical digital-audio input and a 3.5mm 2-channel analog-audio input as well as a hardwired ethernet connector for greater bandwidth on your network. Other connections include a USB port for audio on a USB storage device and an RCA subwoofer output if you want to add a sub to the system.

Normally, the two speakers are paired wirelessly using a proprietary 2.4GHz wireless signal, but a dedicated RJ45 connector on the back of both speakers lets you connect them with an included ethernet cable if you wish. (As with wireless streaming, a wireless connection between the speakers is limited to 48/24 audio, while a wired connection allows up to 96/24.)

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