In this review, we will be comparing Sonus faber Duetto and LSX 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 LSX II first before getting into our more
detailed comparison.
Sonus faber Duetto Key Specs
- 2-way Design
- 700-watt RMS Integrated Amplifier
- 1.1" Soft-Dome Tweeter
- 5.25" Paper-Pulp Woofer
- 37-30k Hz Frequency Response
- 24-bit Max Depth / 192 kHz Max Sample Rate
- Built-in 5.0 Bluetooth
- App Control Feature
- Dimensions (H x W x D): 342.0" x 8.3125" x 11.0625"( 342.0 x 212.0 x 281.0mm )
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 Sonus faber Duetto 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.
**This post contains affiliate links, and I will be compensated if you make a purchase after clicking
through my links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both Sonus faber Duetto and LSX II are 2-way speakers.
| Driver |
Sonus faber Duetto |
KEF LSX II |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.1-inch
|
0.75-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 4.5-inch
|
Sonus faber Duetto features a 1.1" Silk Soft-Dome Tweeter and 1 x 5.25" Paper-Pulp 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
Sonus faber Duetto has a frequency range of 37-30k Hz whereas LSX II has a frequency range of 54-28k Hz. With a minimum frequency of 37Hz, the Sonus faber Duetto 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 Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf 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 Sonus faber Duetto 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.
Sonus faber Duetto Port
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 Sonus faber Duetto's and KEF LSX 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 LSX II has external dimensions of 240 × 155 × 180 mm ( 9.5 × 6.1 × 7.1 inch) .
Sonus faber Duetto is clearly the larger of the two speakers. Its body is 57mm wider, 102mm taller and 101mm deeper than KEF LSX II.
Below you can see the front view size comparison of Sonus faber Duetto and KEF LSX II in scale.
Comparison image of Sonus faber Duetto and KEF LSX 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 LSX II is approximately 279.0cm2 / 43.2inch2. The Sonus faber Duetto requires 114% more surface area than the LSX II which gives it a small disadvantage on placement in tight spaces.
Here is an 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 LSX II on a Media Console
What's in the Box of Sonus faber Duetto?
Here are the items that are included inside the box of Sonus faber Duetto:
2 Wireless powered speakers2 GrillesTwo 6.5-feet AC power cordsRemote controlQuick Start GuideSafety Instructions
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 
High Frequency Response 
RCA Connection 
Height 
Base Surface Area 
Price per pair* 
3.5mm Connection