In this review, we will be comparing two different type of speakers . Q Acoustics M40 is a Floor-standing speaker whereas the LSX II is a Bookshelf speaker.
Let's have a brief look at the main features
of Q Acoustics M40 and KEF LSX II first before getting into our more
detailed comparison.
Q Acoustics M40 Key Specs
- 2-way Design
- 50-watt RMS( 100-watt Peak) Integrated Amplifier
- 0.875" Dome Tweeter
- 2 x 5" Woofer
- 38-22k Hz Frequency Response
- 24-bit Max Depth / 192 kHz Max Sample Rate
- Built-in 5.0 Bluetooth
- Weight:11.80kg
- Dimensions (H x W x D): 710.0" x 10" x 11.7"( 250 x 710 x 296 mm )
KEF LSX II Key Specs
- 2-way Design
- 200-watt RMS Integrated Amplifier
- 11th Generation Uni-Q Driver
- 0.75" Hard-Dome Tweeter
- 4.5" Magnesium/Aluminium alloy Woofer
- 54-28k Hz Frequency Response
- 24-bit Max Depth / 384 kHz Max Sample Rate
- Built-in 4.2 Bluetooth
- App Control Feature
- Weight:3.60kg
- Dimensions (H x W x D): 240.0" x 6.1" x 7.1"( 240 × 155 × 180 mm )
In the following sections, we will get into more detail in order to better understand how the Q Acoustics M40 and KEF LSX II compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both M40 and LSX II are 2-way speakers.
| Driver |
Q Acoustics M40 |
KEF LSX II |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.875-inch
|
0.75-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 5-inch
|
1 x 4.5-inch
|
M40 features a 0.875" Dome Tweeter and 2 x 5" Woofer . On the other hand, the LSX II features a 0.75" Aluminum Hard-Dome Tweeter and 1 x 4.5" Magnesium/Aluminium alloy Woofer .
Frequency Response
M40 has a frequency range of 38-22k Hz whereas LSX II has a frequency range of 54-28k Hz. With a minimum frequency of 38Hz, the M40 can go significantly deeper on the low side and provide stronger bass compared to the LSX II's min frequency of 54Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Floor-standing class in our database.
Low Frequency
Floor-standing Speakers
High Frequency
Floor-standing Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Cabinet Type and Port Position
Both M40 and LSX II 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
Size of a speaker can sometimes become an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare Q Acoustics M40's and KEF LSX II's external dimensions. Q Acoustics M40 has external dimensions of 250 x 710 x 296 mm ( 10 x 28 x 11.7 inch) whereas KEF LSX II has external dimensions of 240 × 155 × 180 mm ( 9.5 × 6.1 × 7.1 inch) .
Q Acoustics M40 is clearly the larger of the two speakers. Its body is 95mm wider, 470mm taller and 116mm deeper than KEF LSX II.
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 Q Acoustics M40 is approximately 740.0cm2 / 114.7inch2 and base area of the KEF LSX II is approximately 279.0cm2 / 43.2inch2. The M40 requires 165% more surface area than the LSX II which gives it a small disadvantage on placement in tight spaces.
What's in the Box of Q Acoustics M40?
Here are the items that are included inside the box of M40:
1x Powered M40 speaker 1x Passive M40 speaker 4x Rear Stabiliser 8x M5 screw 8x Spike Feet 8x Spike Cover 1x Remote Handset (including batteries) 1x Speaker Cable (4 metres) 1x UK Power Cord (2 metres) 1x EU Power Cord (2 metres) 2x Foam Bungs
What's in the Box of KEF LSX II?
Here are the items that come with the LSX II:
2 Wireless powered speakersTwo 6.5-feet AC power cords10-feet Cat-6 interconnect speaker cableRemote control2 AAA batteries Quick Start Guide Important Safety Information Warranty Information Maintenance Guide
Woofer Size 
Price per pair* 
RCA Connection 
High Frequency Response 
App-Based Control 
Height 
Base Surface Area 
Ethernet Connection 
HDMI Input