KEF LSX II vs KEF LS50 Comparison

Speaker to replace

Change

KEF LSX II

Powered Bookshelf | 54-28k Hz

Check price atAmazon›

Change

KEF LS50

Passive Bookshelf | 79-28k Hz

Check price atAmazon›

KEF LSX II

Check price atAmazon›

KEF LS50

Check price atAmazon›

KEF LSX II

See at AMAZON

KEF LS50

See at AMAZON

KEF LSX II vs KEF LS50 Speaker Comparison

In this review, we will be comparing LSX II and LS50, two Bookshelf speakers by KEF. The main difference between these two speakers is that the KEF LSX II is a Powered speaker which means that it has a built-in amplifier inside the speaker body so you don't need an external power amp or an integrated amp whereas the KEF LS50 is a Passive speaker so has to be matched with an amplifier to get any sound from it.

Let's have a brief look at the main features of KEF LSX II and KEF LS50 first before getting into our more detailed comparison.

Key Specs	KEF LSX II	KEF LS50
Brand	KEF United Kingdom · founded 1961	KEF United Kingdom · founded 1961
Design	2-way	2-way
Built-in amplifier	200-watt RMS	—
Uni-Q driver	11th Generation Uni-Q	11th Generation Uni-Q
Tweeter	0.75" Hard-Dome	1" Vented dome
Woofer	4.5" Magnesium/Aluminium alloy	5.25" Magnesium/aluminum alloy
Frequency response	54-28k Hz	79-28k Hz
Sensitivity	—	85 dB
Impedance	—	8 ohms
Power range	—	25-100 watts
Max depth / sample rate	24-bit / 384 kHz	—
Bluetooth	Built-in 4.2	—
App control	Yes	—
Weight	3.60kg / 7.9lbs	7.20kg / 15.8lbs
Dimensions (H x W x D)	9.5" x 6.1" x 7.1" 240 × 155 × 180 mm	11.8" x 7.8" x 10.9" 302.0 x 200.0 x 278.0mm

LSX II and LS50 are members of KEF's LS series of speakers. Below you can find the loudspeakers from this series.

KEF LS Series History

Model	Body	Frequency	Watts RMS	Max Depth / Sample Rate	Woofer
KEF LSX II LT	Bookshelf	54-28k Hz	200-watt	24-bit/384 kHzΩ	1 x 4.5"
KEF LSX II	Bookshelf	54-28k Hz	200-watt	24-bit/384 kHzΩ	1 x 4.5"
KEF LS60 Wireless	Floor-standing	31-24k Hz	1400-watt	24-bit/384 kHzΩ	4 x 5.25"
KEF LS50 Wireless II	Bookshelf	45-28k Hz	380-watt	Yes/384 kHzΩ	1 x 5.25"
KEF LSX	Bookshelf	59-28k Hz	200-watt	24-bit/96 kHzΩ	1 x 4.5"
KEF LS50 Wireless	Bookshelf	79-28k Hz	230-watt	24-bit/192 kHzΩ	1 x 5.25"
KEF LS LUXE	Bookshelf	42-28k Hz	380-watt	/Ω	1 x 6.5"

The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.

Drivers

Both LSX II and LS50 are 2-way speakers.

KEF LSX II

KEF LS50

TweeterWoofer

Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.

Driver	KEF LSX II	KEF LS50
Driver Setup	2-way	2-way
Tweeter	0.75-inch	1-inch
Midrange	-	-
Woofer	1 x 4.5-inch	1 x 5.25-inch

LSX II features a 0.75" Aluminum Hard-Dome Tweeter and 1 x 4.5" Magnesium/Aluminium alloy Woofer. On the other hand, the LS50 features a 1" Aluminum Vented dome Tweeter and 1 x 5.25" Magnesium/aluminum alloy Woofer with a Crossover frequency at 2200Hz.

Frequency Response

LSX II has a frequency range of 54-28k Hz whereas LS50 has a frequency range of 79-28k Hz. With a minimum frequency of 54Hz, the LSX II can go significantly deeper on the low side and provide stronger bass compared to the LS50's min frequency of 79Hz.

The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.

Low Frequency

Bookshelf Speakers

LSX II

LS50

Min

Average

Median

Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.

Cabinet Type and Port Position

Both LSX II and LS50 have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.

If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.

KEF LSX II Port

Physical Specs

The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare KEF LSX II's and KEF LS50's external dimensions. KEF LSX II has external dimensions of 240 × 155 × 180 mm (9.5 × 6.1 × 7.1 inch) whereas KEF LS50 has external dimensions of 302.0 x 200.0 x 278.0mm (11.8 x 7.8 x 10.9inch).

KEF LS50 is clearly the larger of the two speakers. Its body is 45mm wider, 62mm taller and 98mm deeper than KEF LSX II.

Below you can see the front view size comparison of KEF LSX II and KEF LS50 in scale.

Comparison image of KEF LSX II and KEF LS50 Size and External Dimensions

Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited. The base surface area of the KEF LSX II is approximately 279.0cm² / 43.2inch² and base area of the KEF LS50 is approximately 556.0cm² / 86.2inch². The LSX II requires 50% less surface area than the LS50 which gives it a small advantage on placement in tight spaces.

Here is another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:

Size Comparison image of KEF LSX II and KEF LS50 on a Media Console

What's in the Box of KEF LSX II?

Here are the items that are included inside the box of LSX II:

2 Wireless powered speakers
Two 6.5-feet AC power cords
10-feet Cat-6 interconnect speaker cable
Remote control
2 AAA batteries
Quick Start Guide
Important Safety Information
Warranty Information
Maintenance Guide

What's in the Box of KEF LS50?

Here are the items that come with the LS50:

2 Bookshelf loudspeakers
2 Foam port plugs
8 Self-adhesive rubber feet
Owner's Manual
Warranty Registration Card

Reasons to choose KEF LSX II over KEF LS50

Speaker Type	Powered vs Passive	Built-in amplifier
Low Frequency Response	54 Hz vs 79 Hz	Generates deeper bass
Height	240mm vs 302mm	Easier to fit in smaller spaces
Base Surface Area	279cm² vs 556cm²	Takes less floor space
Price per pair*	1299USD vs 1300USD	costs less (*prices may change depending on the seller, location and time)
Ethernet Connection	Yes vs No	High quality streaming over Ethernet
3.5mm Connection	Yes vs No	Connection via 3.5mm AUX input

Reasons to choose KEF LS50 over KEF LSX II

Woofer Size	5.25 inches vs 4.5 inches	Larger woofer

KEF LSX II vs KEF LS50 Specs Table

Detailed comparison of specifications

General	KEF LSX II	KEF LS50
Brand	KEF	KEF
Speaker Type	Powered Stereo Speakers	Bookshelf speakers
Sensitivity	n/a	85 dB
Impedance	n/a	8 ohms
Impedance	n/a	3.2 ohms
Frequency Response	54-28k Hz	79-28k Hz
Amplifier
Watts RMS (Continuous)	200-watt RMS	n/a
Max Bit Depth	24-bit	n/a
Max Sample Rate	384 kHz	n/a
Drivers
Woofer Quantity	1	1
Woofer Size	4.5"	5.25"
Woofer Composition	Magnesium/Aluminium alloy	Magnesium/aluminum alloy
Woofer Surround Material	Rubber	Rubber
Tweeter Size	0.75"	1"
Tweeter Type	Hard-Dome	Vented dome
Aimable Tweeter	No	No
Midrange Driver	No	No
Crossover Frequency	n/a	2200Hz
Firing Direction	rear	rear
Physical Specs
Height	240.0mm (9.4")	302.0mm (11.9")
Width	155.0mm (6.1")	200.0mm (7.9")
Depth	180.0mm (7.1")	278.0mm (10.9")
Weight	3.60kg (7.9lbs)	7.20kg (15.8lbs)
Enclosure	Bass Reflex	Bass Reflex
Finish	n/a	Polymer/Lacquer
Available Colors	Carbon Black, Mineral White, Cobalt Blue, Lava Red, and Soundwave	Black, High Gloss Piano Black, High Gloss Piano White
Mounting Bracket	No	No
Recommended Stand Height	n/a	18-28"
Moisture Resistancy	No	No
Connections
Biamp Inputs	n/a	No
Aux Inputs	3.5mm	n/a
USB Port	USB-C (connects to your computer)	n/a
Phone Input	No	n/a
Subwoofer Output	Wired	n/a
Digital Input	Optical	n/a
HDMI Input	ARC	n/a
Headphone Jack	No	n/a
Ethernet Port	Yes	n/a
Other
Parts Warranty	1 Year	5 Years
Labor Warranty	1 Year	5 Years

Verdict

Different kinds of product: one is active with its amplifier built in, the other passive and needs one. Judge them on how you want to own the system, not just the specs.

Area	Better	Why
Bass	A	KEF LSX II digs deeper - 54Hz against 79Hz.
What you buy	depends	KEF LSX II is a complete system - just add a source. KEF LS50 also needs an amplifier: more money and another box, but you choose it.
Connections	depends	KEF LSX II has Bluetooth, Wi-Fi, streaming and HDMI built in. With KEF LS50 that all comes from the amplifier you pair it with.
Upgrade path	depends	KEF LS50 can be re-amped later and outlive several amplifiers; KEF LSX II ages as one unit.
Size	depends	KEF LSX II is easier to place; KEF LS50 is bigger, which usually goes with fuller bass. Your room decides.
Expandability	A	KEF LSX II: a sub output.
Price	evenly matched	Much the same money ($1,299 vs $1,300 a pair) - though the passive pair still needs an amplifier.

A KEF LSX II B KEF LS50
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.

Which should you choose?

KEF LSX II suits you if you want one box, ready to play, with nothing else to buy. KEF LS50 suits you if you already have an amplifier, want to choose the electronics, or expect to upgrade in stages. Neither is the better speaker in the abstract. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 79Hz anyway, so judge these on the other rows instead. Match it to your room: we rate KEF LSX II the better fit for a mid-size room and a large room, and KEF LS50 for near-field listening and a small room.

And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.