KEF X300A - review

KEF X300A review
An audiophile's desktop computer speaker 
The term computer speakers covers a wide variety of equipment, and we have come a long way from using built in speakers on a laptop to fancy hi fi based setups that can cost upwards of a few thousand dollars.

You can get sound from a nasty $50 pair of plasticky speakers, or you can hookup up your regular stereo system or even a home theatre system to your computer. Whichever way, one key principle is that, crap in garbage out. So use the best source you can. Lossless music will sound better than mp3 and other compressed sources.

If you are willing to go beyond the usual self-powered stuff you see in computer shops, the audiophile slanted companies such as Dynaudio, B&W and now KEF have offerings which do cost more but also offer more for the music orientated computer user, who doesn't want to put up with inferior sound, but doesn't want to clutter his desktop with a whole stereo system.

The elements in a powered speaker are similar. You have the same tweeters and woofers as in a regular speaker, but the amplifier is built into the same box. Options for connections vary from 3.5mm inputs which allow you to plug a similar cable direct from the headphone out of the computer, or RCA / XLR inputs to add other components such as a DAC and some even have built in DACs which allow a USB input from the computer.

The KEF X300A is KEF's first venture into this world, and it is a solid effort. The key features of note:

-       uses class AB amps
-       bi amps tweeter and woofer
-       USB mini type input
-       3.5mm input but no DAC or other digital inputs
-       typical KEF coaxial speaker arrangement
-       two power cords needed and the supplied USB cables are rather short
-       Burr-Brown PCM1754 24/96 asynchronous USB DAC
-       Auto-shut off after 15 min of no input
-       Switch for stand or desktop positions and bungs for rear port
-       Not user selectable universal voltage
-       No subwoofer out

The drivers are derived from the X100 rather than the Blade top of the line model, so it's not the same ones as the LS 50. If you like those round or cylindrical jobs common amongst desktop computer speakers, you are out of luck. It's a bog standard gun metal (one color only) and has cooling fins sticking out of the rear. They weight a substantial 7.5kg and you will need proper stands or a rather significant amount of real estate on your desk to place them. The bottom is flat so you may need some triangular MOPEDs from Auralex to elevate them.

How does it sound?

I use this on a pair of 1m high Atacama stands, about 2m apart in a nearfield listening position about 0.8m away from my sitting position and it is fed by two Audioquest Forest A to mini B USB cables.

I use an iMac circa 2010, and iTunes, with the iTunes volume set to maximum and the gain at about 45%.

 As you expect from coaxial drivers, there is very solid imaging, depth and it's quite neutral, and there is some bass, although bass fiends with a mind to play club music will be disappointed. The main impression is that of a clean accurate sound, with no emphasis on any part of the frequency spectrum and you have absolutely no hiss.

If you are willing to open up the volume a little more, you are rewarded with a distortion free sound, with good weight and dynamics, not inferior to a $1000-1500 CD based setup. Using the USB input rewards you with better weight, scale and a cleaner sound than the 3.5mm socket, and I would recommend buyers take full advantage of the inbuilt DAC, which isn't too shabby and doesn't seem inferior compared to the 2-400$ stand alone ones.

If you listen mainly to vocals, instrumentals and don't crave the bottom octaves this speaker will reward you with a very satisfying sound which is a quantum leap over the inbuilt iMac speakers.

It is still better than the Audio-Engine A2s in detail and scale, and better than the sound from my Denon mini system MCD 38 which I connected using 3.5mm to RCA inputs.

Detractors will highlight the fact that there are no subwoofer outputs, no RCA inputs and the built in DAC does not allow you upgrading capabilities, but like the Mac I use, this system is built on convenience and yet offers a solid sound. You only to plug a USB cable and power, with no additional DAC brick, and further RCA cables to use it and the Mac detects it easily and within seconds you are in audiophile-land and will not really miss your stereo system, especially if you have a solid hard disk of lossless music.

A keeper in my books.
The technical blurb:


Introducing the KEF X300A digital hi-fi speaker system, an active design conceived to partner a PC or Mac, desktop or laptop computer. Simply connect the speakers via a 'distortion free' USB all-digital link to provide high resolution 96kHz/24 bit quality digital input and inter-speaker connection to ensure high definition sound from source to output.  Each speaker features twin class AB audiophile grade amplifiers inside, one for HF and one for LF/MF. Featuring high performance toroidal transformers and high quality DACs, with the X300A you don't need to be an expert to enjoy audiophile sound quality.
System type
_Two-way bass reflex
Drive units
Uni-Q driver array:
HF: 25mm (1in.) vented aluminium dome
LF/MF: 130mm (5.25in.) magnesium/
aluminium alloy
Frequency response
(+/- 3dB)
58Hz - 28kHz
Frequency range
(- 6dB)
49Hz - 45kHz
Max peak SPL
Amplifier type
Twin Class AB
Amplifier power
LF: 50W
HF: 20W
AC power input
US/JP versions: 100-120 VAC, 50/60 Hz
EU/UK/China versions: 220-240 VAC, 50Hz
Analogue input
AUX: 3.5mm stereo jack
Digital input
Sampling rate
USB 2.0: mini USB type B connector
Up to 24-bit
Up to 96kHz, depending on source resolution
Balance control
System volume control
Internal volume
4.7 l
(H x W x D)
Without heatsink:
280 x 180 x 215mm (11.0 x 7.1 x 8.5 in.)
With heatsink:
280 x 180 x 243mm (11.0 x 7.1 x 9.6 in.)
7.5kg (16.5lbs) per speaker


  1. Thanks so much for posting this review. It's quite helpful, and much appreciated considering most of us will never get to hear these speakers before buying them.

    1. I threw out my antique Valve pre & power amps, cd player and Proac speakers and now own a pair of X300a's having auditioned against a pair of LS50's. Here in the UK they cost £600 against £800 for the LS50's I agree with most of this review, though I would add that the base is actually far better than described. If you look at the cost of adding a system that would partner the LS50's adequately, tnen this option is a no brainer.

  2. Thanks for the comments, its a nice speaker, but I won't mistake it for a top end bookshelf and it's no LS 50. But it is certainly a massive step up from the typical desktop PC speaker.

    1. The point I was making was that you can't plug a pair of LS50's straight into your laptop and therefore you get a lot of bangs for your buck with the X300a's. Also, I wouldn't regard the LS50's or any other speaker, for that matter, under £/$ 10000 as high/top end either.

  3. How does this compares to Adam Artist 3? I'm planning to buy one of them but can't decide yet.

  4. anyone use these in a home theater setup? I would sell off my marantz av and pioneer speakers if it is worth it.


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