In this review, we will be comparing Duetto and LS50 Wireless II, two Powered Bookshelf speakers from Sonus faber 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 Sonus faber Duetto and KEF LS50 Wireless II first before getting into our more
detailed comparison.
| Key Specs | Sonus faber Duetto | KEF LS50 Wireless II |
|---|
| Brand | Sonus faber
Italy · founded 1983 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Built-in amplifier | 700-watt RMS | 380-watt RMS (760-watt peak) |
|---|
| Uni-Q driver | — | 12th Generation Uni-Q |
|---|
| Tweeter | 1.1" Soft-Dome | 1" Hard-Dome |
|---|
| Woofer | 5.25" Paper-Pulp | 5.25" |
|---|
| Frequency response | 37-30k 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 | Yes |
|---|
| Weight | 6.80kg / 15lbs | 20.10kg / 44.2lbs |
|---|
| Dimensions (H x W x D) | 13.4375" x 8.3125" x 11.0625"
342.0 x 212.0 x 281.0mm | 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 Duetto and LS50 Wireless II are 2-way speakers.
Sonus faber DuettoKEF 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 |
Sonus faber Duetto |
KEF LS50 Wireless II |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
Duetto features a 1.1" Silk Soft-Dome Tweeter and 1 x 5.25" Paper-Pulp Woofer. On the other hand, the LS50 Wireless II features a 1" Aluminum Hard-Dome Tweeter and 1 x 5.25" Woofer.
Frequency Response
Duetto has a frequency range of 37-30k Hz whereas LS50 Wireless II has a frequency range of 45-28k Hz. With a minimum frequency of 37Hz, the Duetto can go significantly deeper on the low side and provide stronger bass compared to the LS50 Wireless II's min frequency of 45Hz.
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 Duetto 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.
Sonus faber Duetto 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 Sonus faber Duetto's and KEF LS50 Wireless II's external dimensions. Sonus faber Duetto has external dimensions of 342.0 x 212.0 x 281.0mm (13.4375inch x 8.3125inch x 11.0625inch) 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).
KEF LS50 Wireless II is 12mm narrower and 64.2mm shorter than Sonus faber Duetto but it is also 41.3mm deeper.
Below you can see the front view size comparison of Sonus faber Duetto and KEF LS50 Wireless II in scale.
Comparison image of Sonus faber Duetto and KEF LS50 Wireless II 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 Sonus faber Duetto is approximately 595.7cm2 / 92.3inch2 and base area of the KEF LS50 Wireless II is approximately 644.6cm2 / 99.9inch2. The Duetto requires 8% less surface area than the LS50 Wireless II 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 Sonus faber Duetto and KEF LS50 Wireless II on a Media Console
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 Sonus faber Duetto weighs 6.80kg / 15lbs and the KEF LS50 Wireless II weighs 20.10kg / 44.2lbs. This makes the LS50 Wireless II 196% heavier than the Duetto.
Here is a comparison of how Duetto 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 Sonus faber Duetto?
Here are the items that are included inside the box of Duetto:
- 2 Wireless powered speakers
- 2 Grilles
- Two 6.5-feet AC power cords
- Remote control
- Quick Start Guide
- Safety Instructions
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
 Low Frequency Response |
37 Hz
vs
45 Hz
|
Generates deeper bass |
 High Frequency Response |
30k Hz
vs
28k Hz
|
Generates higher frequency |
 Base Surface Area |
595cm2
vs
644cm2
|
Takes less floor space |
 RCA Connection |
Yes
vs
No
|
Connection via RCA input |
 Height |
277mm
vs
342mm
|
Easier to fit in smaller spaces |
 Price per pair* |
2999USD
vs
3999USD
|
costs less (*prices may change depending on the seller, location and time) |
 3.5mm Connection |
Yes
vs
No
|
Connection via 3.5mm AUX input |
| General |
Sonus faber Duetto |
KEF LS50 Wireless II |
| Brand |
Sonus faber |
KEF |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
37-30k Hz |
45-28k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
700-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 |
5.25" |
5.25" |
| Woofer Composition |
Paper-Pulp |
|
| Tweeter Size |
1.1" |
1" |
| Tweeter Type |
Soft-Dome |
Hard-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
342.0mm (13.5") |
277.8mm (10.9") |
| Width |
212.0mm (8.3") |
200.0mm (7.9") |
| Depth |
281.0mm (11.1") |
322.3mm (12.7") |
| Weight |
6.80kg (15lbs) |
20.10kg (44.2lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Black,Walnut |
n/a |
| Mounting Bracket |
No |
|
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
RCA |
3.5mm |
| USB Port |
Service only |
Service only |
| Phone Input |
No |
No |
| Subwoofer Output |
mono-RCA |
mono-RCA |
| Digital Input |
Optical |
1 |
| HDMI Input |
eARC |
eARC |
| Headphone Jack |
No |
No |
| Ethernet Port |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
2 Yrs (3 Yrs registered) |
3 Year w/ registration |
| Labor Warranty |
2 Yrs (3 Yrs registered) |
3 Year w/ registration |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your sources and what you listen to.
| Area | Better | Why |
|---|
| Bass | A | Sonus faber Duetto digs deeper - 37Hz against 45Hz. A subwoofer would even that out. |
| Built-in power | A | Sonus faber Duetto has the bigger amplifier (700W vs 380W RMS). |
| Connections | evenly matched | The same set of inputs and streaming options. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | Sonus faber Duetto: a sub output; KEF LS50 Wireless II: a sub output. |
| Price | B | KEF LS50 Wireless II is cheaper - $2,999 against $3,999, about 25% less. |
A Sonus faber Duetto 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: Sonus faber Duetto measures better, KEF LS50 Wireless II costs about about 33% more% 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 45Hz anyway, which makes the cheaper KEF LS50 Wireless II much easier to justify. Think about the whole system, not just the speakers: the roughly $1,000 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.