Hi-Fi Plus: Naim HDX Hard Disk Player

Tomorrow’s World

[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.