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Kenwood KMM-257U Single DIN FM/USB/iPod/FLAC Head Unit

Product Details
Manufacturer:  Kenwood
Website: http://www.kenwood-electronics.co.uk/products/car/cd_receivers/ipod_iphone/KMM-257/details/
Typical Selling price: £59.95

In A Nutshell
Skinny wee single DIN head unit with no disc mech inside but rather a better set of processing and like the ancient and rapidly Appled-to-Death Music Keg (called KHD-C710) which acted like a CD changer, this headunit can decode FLAC 16 files. Thus playing finer SQ from the 2.5 Volt single output than a thousand pound CD player can, for bit depth and dynamics! Looks ordinary but is the harbinger of high SQ digital audio in-car, without bloody Digital Rights Management. Awesome bargain at what will sell for under £50 in the real world.

Overall                            9.4
Sound Quality                  10
Appearance/Display          9
Ease Of Use/HMI              10
Features                            9
Value For Money             10

What It Is
It’s a single DIN head unit with no CD deck, and has a USB socket as well as simple audio auxiliary input on the front right . The really big deal is the FLAC capability. It will read SD cards as well as USB sticks. As this is a first unit, it reads FLAC 16 but not yet FLAC 24 files. However, I am reliably informed that there will be a new unit later with more outputs and that generation will go directly to FLAC 32 capability.

Editor Review : Kenwood KMM-257 Single DIN FM/USB /iPod//FLAC Head Unit
I was delivered this one Friday a good while back – but that was a bit previous of us, long before the unit was on sale and I had a production sample in a wrong-box. I then wheedled my way into being allowed access to the Bowers & Wilkins Society of Sound and have downloaded some FLAC 16 files from all sorts of flavours. I confess, I didn’t download any of Bass Mekanik’s stuff from Bandcamp, but I do have his stuff on WMA..

How Well Does It Work?
So simple question. I fired it up, playing it through a rather lovely Soundstream Ref 4.400 amplifier of reference quality – like it says - into some high quality speakers with tiny bullet tweeters and sweet midband capability as well as a bit of bass and I was just delighted.

It reminded me of the time I got a hold of the rare Sony MEX-DV1000 DVD and SACD player and played some SACD version of the Pink Floyd Dark Side of the Moon album! Only this was a bit of posher stuff from an outfit called Three Cane Whale… as well as some live stuff from Peter Gabriel in Athens.

The sound quality was astonishing and I looked at that cheap little box and marvelled. You could have seen me doing it…marvelling.

Highs were crisp and had no sibilance and yet the tinkly bits were even tinklier. And the sense of space at the live gig, as well as every damn fingernail’s edge on the strings of the throwback virtuoso mandolins and lutes and stuff of Three Cane Whale, were amazing. It was just better than any digital thing I have heard since I listened to a Sony 48 track digital tape machine recorded at 48kHz at Stirling Audio in pro-land many years back!

I could piffle on about the rest – it was a fifty quid deck in reality, with simple urges but just check out that mad specification as far as digital doodarery is concerned.

For right now, Kenwood have a digital whatnot, what no-one’s got.

Why Buy It?

It is almost disposably cheap at half the price of a fat tank of fuel and allows you to store and start playing on the road, with the joyous purity that can be FLAC. And furthermore, this is the FIRST fully digital device since CD that I have really enjoyed. I hate the piffle of DRM and Apple’s complex ecosystems and nil likelihood of continuing stress-free use. I loathe the low res of shitty MP3.

Welcome to the finish of The DIGITAL DAWN!

I feel like the Dark Ages of LowFi common-use digital audio have ended and choice for excellence is once more in our hands. Make no mistake, there are FAR more sophisticated machines than this wee spudney out there from Alpine and Pioneer and Clarion alike…but this is State of The Art for digital files. (Now THAT is going to put a stinky wee-smelling cat amongst the lily-white pigeons!)

Full Features & Specifications

Key Features
Mechaless USB receiver
Full removable front panel
USB 1.0/2.0 high speed port
iPod/iPhone direct control
MP3/WMA/AAC/WAV playback
FLAC (Free Lossless Audio Codec) playback
Short depth chassis (30% less than CD-receivers)
Tuner preset hold without back-up power

General Features
Protection soft case for faceplate
Red Key Illumination
Rotary Encoder & Control Knob
Accent key
Attenuator with Smooth Volume Return
Touch Sensor Tone
Digital Clock (24H)
All-off Select (20/40/60 minutes)
Built-in Connector Molex 16 pin
ISO connector
Fluorescent (FL) Tube Display, 13 segments x11 Characters
Dimmer Control: two steps - Manual
Demo Mode
Russian text display
Red Triangle Illumination
Red Key illumination
Radio Data System
Radio Text
Program Type Function (PTY)
Traffic Information
FM Reception
AM (MW/LW) Reception
24 Presets (18FM / 3LW / 3MW)
Mixed preset memory (FM & AM) 6 presets
Up/Down Seek Tuning
Tuning mode (Auto1 / Auto2 / Manual)
FM Stereo / Mono Selector

USB Features
USB terminal  Front side
Type: USB 1.1/USB 2.0 Full Speed
Kenwood Music Editor Lite Compatible
Repeat/Scan/Random search
1A current capability

iPod Features
Made for iPod & iPhone
USB Digital connection (1 wire) with optional cable KCA-iP102
Alphabet search
Skip search
App & iPod control mode
2 Speed search
High speed search
Reverse browsing
Works with iPod Classic * 80G, 120G & 160G
Works with iPod Video * 5th/6th generation
Works with iPod Touch * 1st/2nd/3rd and 4th generation
Works with iPod Nano * 1st/2nd/3rd/4th/5th/6th Gen
Works with iPhone *
Battery charge + power control
* Always update to latest Apple firmware

Audio Features
Maximum Output Power 50W x 4
Auxiliary input Front Mini-jack
Pre-out 1 RCA
Pre-out Output Level: 2.5V
Preout Rear / Subwoofer Switchable
Subwoofer Reference Level Adj.
Source Tone Control & Memory
Balance/Fader/Loudness Control
-20dB Attenuator with smooth Volume Return
System Q
Preset EQ
Bass Boost Circuit
Low-pass Filter

iPod Digital Connection (1 Wire)
Front USB & AUX Input
DC-Cord Molex to ISO
OEM Wired Remote Control
Power Control (P.CON) wire
2-way (Tel/Navi) mute wire

Tuner Specifications
FM Frequency range (50kHz step) 87.5MHz ~ 108MHz
FM Usable Sensitivity 1μV/75ohm (S/N 26dB)
FM Quieting Sensitivity 2.5μV/75ohm (S/N 46dB)
FM Frequency Response 30Hz ~ 15kHz (± 3dB)
FM Signal to noise ratio (Mono) 63dB
FM Stereo Separation (1kHz) 40dB
MW Frequency Range 531kHz ~ 1611kHz (9kHz step)
MW Frequency step 9kHz
MW Usable Sensitivity 36μV
LW Frequency Range 153kHz ~ 279kHz (9kHz step)
LW Usable Sensitivity 57μV

USB Specifications
USB Version compatibility USB 1.1/2.0 full speed
File System FAT 32/16/12
Maximum Supply current 1000mA
D/A Converter 24 bit
MP3 Decode Compliant with MPEG-1/2 Audio Layer-3
WMA Decode Compliant with Windows Media Audio
AAC Decode AAC-LC ".m4a" files
WAV Decode RIFF waveform audio format (Linear PCM only)

Audio Specifications
Maximum Power 50W x 4
Output Power (DIN45324,+B=14.4v) 30W x 4
Preout Level 2500mV / 10kOhm,
Preout Impedance ≤ 600Ohm
Speaker Impedance 4Ohm ~ 8Ohm
AUX Frequency Response 20Hz ~ 20kHz (±1dB)
AUX Maximum Input Voltage 1200mV
AUX Input Impedance 10kOhm
Bass Tone Control 100Hz ±8dB
Middle Tone Control 1kHz ±8dB
Treble Tone Control 12.5kHz ±8dB

Release keys 2 pieces
Escutcheon plate
Installation cage
DC cord (Molex to ISO) 23 cm

General Specifications
Operating voltage 14.4V (11 ~ 16V Allowable)
Maximum Current Consumption 10A
Dimensions (WxHxD) 182 x 53 x 107mm
Weight 640gr

Kenwood’s website is here: http://www.kenwood-electronics.co.uk/


having converted over 200gb of my music to flac this is great news. so how do you play flac from sd? i take it you have to run a wire from the front to a card reader? bit messy if thats all the connection it has.... BUT add a sd card reader behind the faceplate, then add the DAB tuner and ill buy one! i am a bit fan of the current kenwood looks but its just a shame most of the tech is geared towards an iplod of which i don't own and have no intention of owning.

so adam, if it needs a temporary home for a long term evaluation just ask /wink.png' class='bbc_emoticon' alt=';)' />
Thanks fo this review confirming the quality of the unit !
Bodhisattva, the kmm 257 doesn't have a SD card reader, it cost 60€ here in France, the kmm 357 sd add the SD card reader behind the removable faceplate for 20€ more at 80€, with fancy lights colors too. [url="http://www.kenwood.eu/products/car/receivers/all/KMM-357SD/"][url][url][url]http://www.kenwood.eu/products/car/receivers/all/KMM-357SD/[/url][/url][/url][/url]
1/3 of the price for a card reader....
We don't have DAB radio in France now, which is a shame.

"However, I am reliably informed that there will be a new unit later with more outputs and that generation will go directly to FLAC 32 capability".
Wow now I have the doubt to wait until this one is released rather than buy this one !
The price should be more expensive too... I guess I can't wait very long !

Adam, is there any chance to open it and take High resolution picture of the inside component, to check what kind of chips are used to decode the flac and the DAC
As for some Alpine unit, may a tweak can add digital out of it, to raise the sound quality again.
I dont understand why Kenwood made a FLAC compatible head unit then made it a budget deck? And surely FLAC is only indetical (bit perfect) to a CD player, and not "better than" by defenition of being lossless?
I don't understand too, maybe it's a reception test about flac files ?
FLAC could be identical to CD if ripped from CD (16 bits 44100 hz).
Could be better if ripped from SACD or DVD audio (24/96000) or even Studio Masters (24-32 bits / 192 khz).
And don't need the drive mechanic, avoid moving part inside the deck and car vibrations.

I bought one of these but when the Traffic Information is on I have a problem with reception when listening to BBC Radio 4.  It's like when you drive through a tunnel and lose the signal for a few seconds.  If I switch TI off the problem goes away, but that means no warning of traffic jams etc.


Has anyone else had this problem?

Just got a KMM-361SD for £67 from Amazon. Buy one you won't be disappointed.