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Sonus faber Duetto vs KEF LSX II Comparison

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Sonus faber Duetto

Powered Bookshelf | 37-30k Hz

Sonus faber Duetto
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KEF LSX II

Powered Bookshelf | 54-28k Hz

KEF LSX II
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Sonus faber Duetto Sonus faber Duetto
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KEF LSX II KEF LSX II
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Sonus faber Duetto
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KEF LSX II
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Sonus faber Duetto vs KEF LSX II Speaker Comparison

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

Sonus faber Duetto
LSX II
Min
Average
Max
High Frequency

Bookshelf Speakers

Sonus faber Duetto
KEF LSX II
Min
Average
Max

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
Sonus faber Duetto Port

KEF LSX II  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.

Sonus faber Duetto vs KEF LSX II Size Comparison - Front View
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:

Sonus faber Duetto vs KEF LSX II Size Comparison on a Media Console
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 speakers
  • 2 Grilles
  • Two 6.5-feet AC power cords
  • Remote control
  • Quick Start Guide
  • Safety Instructions
  • What's in the Box of KEF LSX II?

    Here are the items that come with the 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

  • Reasons to choose Sonus faber Duetto over KEF LSX II
    Woofer Size 5.25 inches vs 4.5 inches Larger woofer
    Low Frequency Response 37 Hz vs 54 Hz Generates deeper bass
    High Frequency Response 30k Hz vs 28k Hz Generates higher frequency
    RCA Connection Yes vs No Connection via RCA input

    Reasons to choose KEF LSX II over Sonus faber Duetto

    Height 240mm vs 342mm Easier to fit in smaller spaces
    Base Surface Area 279cm2 vs 595cm2 Takes less floor space
    Price per pair* 1299USD 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
    Sonus faber Duetto vs KEF LSX II Specs Table
    Detailed comparison of specifications
    General Sonus faber Duetto KEF LSX II
    Brand Sonus Faber KEF
    Speaker Type Powered Stereo Speakers Powered Stereo Speakers
    Frequency Response 37-30k Hz 54-28k Hz
    Amplifier
    Watts RMS (Continuous) 700-watt RMS 200-watt RMS
    Max Bit Depth 24-bit 24-bit
    Max Sample Rate 192 kHz 384 kHz
    Drivers
    Woofer Quantity 1 1
    Woofer Size 5.25" 4.5"
    Woofer Composition Paper-Pulp Magnesium/Aluminium alloy
    Woofer Surround Material n/a Rubber
    Tweeter Size 1.1" 0.75"
    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") 240.0mm (9.4")
    Width 212.0mm (8.3") 155.0mm (6.1")
    Depth 281.0mm (11.1") 180.0mm (7.1")
    Weight n/a 3.60kg (7.9lbs)
    Enclosure Bass Reflex Bass Reflex
    Available Colors Black,Walnut Carbon Black, Mineral White, Cobalt Blue, Lava Red, and Soundwave
    Mounting Bracket No No
    Grille Yes n/a
    Moisture Resistancy No No
    Connections
    Aux Inputs RCA 3.5mm
    USB Port Service only USB-C (connects to your computer)
    Phone Input No No
    Subwoofer Output mono-RCA Wired
    Digital Input Optical Optical
    HDMI Input eARC ARC
    Headphone Jack No No
    Ethernet Port Yes Yes
    Other
    Parts Warranty 2 Yrs (3 Yrs registered) 1 Year
    Labor Warranty 2 Yrs (3 Yrs registered) 1 Year

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