Naim HDX Hard Disk Player (Hi-Fi+)

Music servers and computer audio,
Naim Audio HDX Hard-Disk Player
Naim HDX Hard Disk Player (Hi-Fi+)

[This review originally appeared in issue 65 of Hi-Fi Plus magazine, which is published in the U.K.]

The Naim HDX has rguably courted more controversy than any hi-fi device since the CD player. So, what’s caused all the fuss? The HDX is a hard disk player, in Naim’s inimitable style. It combines regular computer technology with Naim’s expertise in analogue and digital music circuitry and power supply design, and also takes advantage of some of the lessons learned in developing the company’s NaimNet custom install devices.

The computer-side parts are effectively an off-the-shelf PC (specifically a Mini-ITX design sporting a 1.5GHz Via C7 CPU), a pair of 400GB hard disk drives, a CD-ROM drive and quiet computer power supply. That’s met by Naim’s own custom-made PCI board; this combines PCI bridge, audio controller and high-precision clock, each with its own power supply regulation. This necessitated Naim writing its own driver software for the device, to make sure the transfer of data from the hard disk to the custom PCI board is performed as smoothly (and with as little processor action) as possible.

Once we leave the computer side, the HDX begins to look more Naim-y under the skin. There’s a four-layer custom audio-board, which drives both analogue (DIN and phono) and digital (toslink and coaxial S/PDIF) outputs and features a Burr Brown PCM1791A digital to analogue converter chip. Once again, high-quality clocks and plenty of power supply isolation are a common factor, and the analogue board uses a microcontroller that lies in slumber when music is playing on only wakes when accessing new tracks. This is the one upgradable aspect of the player; again in the Naim style, this can be beefed up by something like a Naim 555PS power supply, or a separate DAC. Granted, adding a 555PS to a HDX makes for a very expensive server indeed, but Naim’s power supply upgrades are key to the company’s ethos. It’s not a power supply upgrade to the computer side, but confers the same benefits to the audio sideas upgrading the power supply to a preamp.

The NaimNET connection means you can run six audio streams simultaneously from the HDX. It also includes the thoroughly clever system of giving the front panel a different IP address to the computer side. This means the computer part can access online music stores or databases, while the control architecture can be driven from other locations. It also means the HDX can be controlled from a webtablet like the Nokia N8.

There’s one big – and thoroughly deliberate – omission; no CD burning facility. This is entirely understandable when coming from a company with its own record label and therefore a good understanding of intellectual property rights. Similarly, the HDX does not automatically rip CDs to its hard drive(s). Instead, it gives the option of playing the CD as a CD, meaning those bringing CDs to a party do not end up making an illegal copy on the HDX. You still get all the advantages of the HDX’s metadata control and database lookup facilities when playing that CD, but it’s just that the moment the disc is removed, the menu system removes all record (‘depopulating the menus’ in Naim-speak) of that disc. Yes, we’d all rather have the facility to burn discs and rip our friends music, but it’s crossing a copyright line that Naim is keen to prevent.

Naim says the player should be powered up permanently (except during thunderstorms, of course), and suggests a good five-day warm-up to bring the player to its best. In fairness, I spent my first five days with the Naim HDX stuffing it full of CDs to see just how crash-proof and how good the player was at finding obscure records on databases, but the sound did seem to improve over those days – as is commonplace with Naim products.

Although the HDX will support FLAC and MP3 files, and high-res PCM audio from downloads, it does not offer anything other than full uncompressed WAV rips from CD. This means the internal 400GB disc will only store up to about 600 CDs (the second HDD is for back-up), but you can add network attached storage (‘NAS’) boxes for larger collections.

Naim’s ripping technology uses secure mode ripping (this means an average CD will take several minutes) and preserves track lead-ins and outs as standard; this makes your ripped discs sound more like you remember them, not simply tracks stored on a computer.

The HDX will rip more accurately than discs ripped in burst mode, but so will any other ripping software using secure ripping. Bit-perfect is bit-perfect, whichever way it arrives. I ripped the same file using the HDX, Exact Audio Copy and iTunes (all in WAV) and compared the results – they were identical.

A more disputed claim is whether there’s a need to store in WAV, as many servers now use lossless compression and there’s no notional difference in sound quality between the original and lossless form (if there was a difference, it wouldn’t be ‘lossless’, goes the logic). Many – including Naim, it seems – reject that concept as a matter of course. If you receive FLAC or MP3, AAC or even WMA files, the HDX will cope with them, but there’s no pathway to rip discs in anything other than their original form.

Connection is easy, although a little different from most hi-fi systems. The usual phono connection to a preamp (DIN if you are a Naim user), the big Burndy link for a power supply or maybe a S/PDIF link for digital. But then, there’s the connection for a screen and an Ethernet connection for linking to a router. There’s no wi-fi connection and Naim recommends linking the HDX to the outside world using a wired connection. Generally, the IP connection is straightforward, and up and running in seconds.

We tried to floor the HDX by feeding it a very broad range of discs. Some of them were designed to check the speed and performance of the rip – discs that look like they’ve been read by a cold chisel instead of a laser – and others that challenge the abilities of the database software. In both cases, the HDX acquitted itself well. The scratched discs took longer to rip than clean ones, but the result was the same. The player has a limited lookup table built-in, but when going to AMG (and, failing that, FreeDB) it can load up details and album covers with about a 98% certainty (of the first 100 discs I loaded up, only Popa Chubby and Schoenberg tripped it up, and even then it served up album and track data).

Using and abusing the player as much as possible rarely threw out problems and the player required a hard reset twice in two weeks of stern punishment – at the same time a feeding discs into a PC caused it to crash out, making a tweeter ripping chirp every few hours. A hard reset takes a long time to power down or boot up, though and if you are used to pressing play a few seconds after powering up a CD player, the HDX will leave you disappointed… there’s a several minute long gap between turning the thing on and getting the menus up and running.

We played the HDX through a thoroughly non-Naim system (a Sugden A21SE amp and ProAc Studio 140 loudspeakers) and compared it with a Cyrus CD8se CD player with PSX-R power supply and to a PC with a DAC.

There’s a distinctive ‘Naiminess’ to the sound of the HDX. It has that beat-driven musicality that makes the player prove so seductive at playing rock music. And, with a few hundred CDs loaded up, that ‘seductive’ turns into track after track of air guitar around the living room. There’s also a directness and precision to the sound that’s the antithesis of vinyl, and even challenges CD on the timing and solidity stakes.

What the Naim HDX does – and does brilliantly – is cope with the architecture of the music, at once making music seem more integrated and delineating the spaces around the notes with as much finesse as the notes themselves. In that respect, it plays music with the economy of a BB King, which is a rare treat.

It also makes music a great deal of fun. We all have our guilty secret recordings that we feel the need to wig out to; forget the surface intellectualising of listening to genteel Mendelssohn, this is the bad-boy stuff you never quite got over as a teenager. You can guarantee the Naim HDX will make you reach for that CD and rip it. Which is why the next recipient of my review sample will had to clean out all the AC/DC, Muse and Van Halen tracks off the HDD. And the joys of being able to reach for Back in Black, Stockholm Syndrome or Ain’t Talkin’ ‘bout Love in a matter of seconds any time of the day or night is something to relish… and something your neighbours will seriously come to hate you for.

Like a lot of Naim equipment, the HDX tends to lead you toward the rock end of your musical spectrum. But that may be because those who have reviewed it tend to play music at the rock end of the spectrum. I had no problems listening to a fair selection of older jazz, folk and even pumped the thing full of unhealthy amounts of Richard Strauss. Whatever you play, though, it seems to free up your inner rocker; I found myself air conducting Strauss, playing air trumpet to Louis Armstrong and playing air fiddle to the folksy stuff. I still got a lot of the cerebral aspects of the music, but this made you think entertainment first and foremost.

In some respects though, the performance is secondary. It’s a good player, but that’s not the point. What Naim has done with the HDX is make computer audio painless. Although you couldn’t get exactly the same performance as you can get from the HDX, you might be able to get close using a PC and a good DAC. However, the steps you have to go through to simply rip a disc, store it and access it make such a thing difficult without turning your hi-fi into a workstation. You can run the HDX just using the display panel if you want.

This sounds trivial, but is the key to the HDX’s success. It’s also some explanation as to why the HDX has received such flak in cyberspace. Those who are into their hi-fi and computers enough to post to forums are not necessarily the kind of people who will ‘get’ the HDX. Instead, think of the Naim player as a CD player with a very good memory and an interest in musicology for someone who is loathe to use a PC in the living room.

Eventually, we compared the Naim HDX to a CD and a PC solution, with no considerations made toward price. All three produce a comparable performance; the Cyrus duo has the accent on ‘clean’, the PC leads the field when it comes to stark detail and the Naim wins in the sheer enjoy-the-experience stakes (in fairness, an iTunes solution would make the PC more user-friendly, but you still think of it as a computer, where the Naim HDX is every bit the music player). When playing directly off the CD, the Cyrus was the winner by a hair, but both this and the Naim were somewhat more musical sounding than the no-name transport mech inside the PC. 

The Naim HDX’s software isn’t perfect; it could do with some Apple-esque user-chumminess and the powerful sorting process of the Sooloos, but it’s certainly not human-hostile. In fact, it’s virtually as easy to use as a Naim CD player, as you might expect. Because it’s the migration product for those who think a computer is for workin’ and surfin’ and a hi-fi is for listenin’.

I suspect the HDX will always divide people. There will be those who think it’s ‘just a computer’ and others who think it’s Naim’s best product since the CD 555. Personally, I think it’s a clever product that starts hi-fi traditionalists (many of whom love Naim products) on the road to 21st Century music delivery systems without too many tears. And for that reason, it’s a lot smarter move on the company’s account than many people credit.

Technical Specifications

Naim HDX Hard Disk Player

Type: Hard Disk player
Features: Rips CDs to WAV only, 2x 400GB hard disk drives internally, NAS external support for increased capacity and back-up
Line outputs: DIN and RCA
Frequency response: 10Hz-18kHz ± 0.1dB
Output levels: 2.1V rms at 1kHz
Output impedance: 22 Ohms max
Phase response: Linear, absolute phase correct
Distortion and noise: <0.1% 10Hz-18kHz at full level
Disc compatibility: Red book compatible CD, CDR & CDRW
Audio Files supported: WAV, MP3, AAC, FLAC, WMA
Mains supply: 100-120V, 220-240V, 50/60Hz
Dimensions (H x W x D): 87 x 432 x 314mm
Weight: 10.8kg

Price: £4,500

Manufacturer: Naim Audio
Tel: + 44 (0) 1722 426600


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