In this review, we will be comparing M20 HD and LS50 Wireless II, two Powered Bookshelf speakers from Q Acoustics and KEF. Being Powered speakers, they both have built-in amplifiers so you don't need an external power amp or an integrated amp to power them.
Let's have a brief look at the main features
of Q Acoustics M20 HD and KEF LS50 Wireless II first before getting into our more
detailed comparison.
| Key Specs | Q Acoustics M20 HD | KEF LS50 Wireless II |
|---|
| Brand | Q Acoustics
United Kingdom · founded 2006 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Built-in amplifier | 128-watt RMS | 380-watt RMS (760-watt peak) |
|---|
| Uni-Q driver | — | 12th Generation Uni-Q |
|---|
| Tweeter | 0.875" Dome | 1" Hard-Dome |
|---|
| Woofer | 5" | 5.25" |
|---|
| Frequency response | 55-22k Hz | 45-28k Hz |
|---|
| Max depth / sample rate | 24-bit / 192 kHz | Yes / 384 kHz |
|---|
| Bluetooth | Built-in 5.0 | Built-in |
|---|
| App control | — | Yes |
|---|
| Weight | 5.10kg / 11.2lbs | 20.10kg / 44.2lbs |
|---|
| Dimensions (H x W x D) | 10-15/16" x 6-11/16" x 12-3/16"
278.0 x 170.0 x 310.0mm | 10.9375" x 7.875" x 12.6875"
277.8 x 200.0 x 322.3mm |
|---|
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both M20 HD and LS50 Wireless II are 2-way speakers.
Q Acoustics M20 HDKEF LS50 Wireless II
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Q Acoustics M20 HD |
KEF LS50 Wireless II |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.875-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5-inch
|
1 x 5.25-inch
|
M20 HD features a 0.875" Dome Tweeter and 1 x 5" Woofer. On the other hand, the LS50 Wireless II features a 1" Aluminum Hard-Dome Tweeter and 1 x 5.25" Woofer.
Frequency Response
M20 HD has a frequency range of 55-22k Hz whereas LS50 Wireless II has a frequency range of 45-28k Hz. With a minimum frequency of 45Hz, the LS50 Wireless II can go significantly deeper on the low side and provide stronger bass compared to the M20 HD's min frequency of 55Hz.
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
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 M20 HD and LS50 Wireless 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.
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 Q Acoustics M20 HD's and KEF LS50 Wireless II's external dimensions. Q Acoustics M20 HD has external dimensions of 278.0 x 170.0 x 310.0mm (10-15/16 x 6-11/16 x 12-3/16inch) whereas KEF LS50 Wireless II has external dimensions of 277.8 x 200.0 x 322.3mm (10.9375 x 7.875 x 12.6875inch).
Q Acoustics M20 HD is 30mm narrower and 12.3mm less deeper than KEF LS50 Wireless II but it is also 0.19999999999999mm taller.
Size, drawn to scale
Both speakers and both views share one scale, so everything here is directly comparable. Hover a box for its dimensions.
One scale for both, standing on the same surface and pushed back to the same wall, so the deeper one visibly sticks out further.
KEF LS50 Wireless II needs about 22% more floor or shelf area.
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 M20 HD is approximately 527.0cm2 / 81.7inch2 and base area of the KEF LS50 Wireless II is approximately 644.6cm2 / 99.9inch2. The M20 HD requires 18% less surface area than the LS50 Wireless II which gives it a small advantage on placement in tight spaces.
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The Q Acoustics M20 HD weighs 5.10kg / 11.2lbs and the KEF LS50 Wireless II weighs 20.10kg / 44.2lbs. This makes the LS50 Wireless II 294% heavier than the M20 HD.
Here is a comparison of how M20 HD and LS50 Wireless II's weights compare with the average, max and min weights in Powered Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Q Acoustics M20 HD?
Here are the items that are included inside the box of M20 HD:
- Powered speaker
- Passive speaker
- 6-feet AC power cord
- Remote control
- 2 AAA batteries
- 13-feet Speaker wire
- 59-inch Optical digital cable
- 2 Foam port plugs
- Owners Manual
What's in the Box of KEF LS50 Wireless II?
Here are the items that come with the LS50 Wireless II:
- 2 Wireless powered speakers
- Two 6.5' AC power cords
- 10' Cat-6 interconnect speaker cable
- Remote control
- 2 \"AAA\" batteries
- Quick Start Guide
- Important Safety Information
- Warranty Information
 Base Surface Area |
527cm2
vs
644cm2
|
Takes less floor space |
 Price per pair* |
599USD
vs
2999USD
|
costs less (*prices may change depending on the seller, location and time) |
 RCA Connection |
Yes
vs
No
|
Connection via RCA input |
 Woofer Size |
5.25 inches
vs
5 inches
|
Larger woofer |
|
Low Frequency Response |
45 Hz
vs
55 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
22k Hz
|
Generates higher frequency |
 App-Based Control |
Apple iOS, Android
vs
None
|
Control the speaker via an app |
 Height |
277mm
vs
278mm
|
Easier to fit in smaller spaces |
 Ethernet Connection |
Yes
vs
No
|
High quality streaming over Ethernet |
 USB Port |
Service only
vs
No
|
USB port adds flexibility |
 HDMI Input |
eARC
vs
No
|
Connect HDMI sources directly |
| General |
Q Acoustics M20 HD Wireless Music System |
KEF LS50 Wireless II |
| Brand |
Q Acoustics |
KEF |
| Speaker Type |
Powered stereo speakers |
Powered Stereo Speakers |
| Frequency Response |
55-22k Hz |
45-28k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
128-watt RMS |
380-watt RMS |
| Watts Peak (Max) |
n/a |
760-watt RMS |
| Max Bit Depth |
24-bit |
Yes |
| Max Sample Rate |
192 kHz |
384 kHz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5" |
5.25" |
| Woofer Composition |
|
|
| Tweeter Size |
0.875" |
1" |
| Tweeter Type |
Dome |
Hard-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
278.0mm (10.9") |
277.8mm (10.9") |
| Width |
170.0mm (6.7") |
200.0mm (7.9") |
| Depth |
310.0mm (12.2") |
322.3mm (12.7") |
| Weight |
5.10kg (11.2lbs) |
20.10kg (44.2lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Black, White, Walnut |
n/a |
| Mounting Bracket |
No |
|
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
3.5mm, Stereo RCA |
3.5mm |
| USB Port |
USB-B |
Service only |
| Phone Input |
No |
No |
| Subwoofer Output |
mono-RCA |
mono-RCA |
| Digital Input |
Optical |
1 |
| HDMI Input |
No |
eARC |
| Headphone Jack |
No |
No |
| Ethernet Port |
No |
Yes |
Other |
|
|
| Parts Warranty |
2 Years |
3 Year w/ registration |
| Labor Warranty |
2 Years |
3 Year w/ registration |
These sit in different price classes - KEF LS50 Wireless II costs roughly 5x what Q Acoustics M20 HD does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Bass | B | KEF LS50 Wireless II digs deeper - 45Hz against 55Hz. |
| Built-in power | B | KEF LS50 Wireless II has the bigger amplifier (380W vs 128W RMS). |
| Connections | B | KEF LS50 Wireless II adds Wi-Fi and HDMI. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | Q Acoustics M20 HD: a sub output; KEF LS50 Wireless II: a sub output. |
| Price | A | Q Acoustics M20 HD is cheaper - $599 against $2,999, about 80% less; arguably a different class. |
A Q Acoustics M20 HD B KEF LS50 Wireless II
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?
The usual trade-off: KEF LS50 Wireless II measures better, Q Acoustics M20 HD costs about about 5x the price% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 55Hz anyway, which makes the cheaper Q Acoustics M20 HD much easier to justify. Think about the whole system, not just the speakers: the roughly $2,400 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
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.