Our full review of the Naim ND 555 is below, but you can read the original magazine pages from Audio Esoterica as PDFs by clicking the picture above. These pages include an interview with Steve Sells, Naim’s Technical Director of Electronics, which can be read online separately here.

As we lugged three boxes — two large heavy ones, and a medium lighter one — from the car up the many steps to the music room, we couldn’t help thinking that this seemed a lot of weight for a streaming source. The heavier boxes contained not one but two required components — Naim’s new top-of-the-heap ND 555 network player itself, and then the CD 555 PS, a unit for which the suffix is more descriptive than the prefix, it being the required standalone power supply as supplied for review (this was the DR version, now redesignated the 555 PS DR, which is a requisite for the ND 555, and costs an additional $13,250).

The third and lighter box contained two black accessories boxes, one of which yielded a pair of finger-thick cables terminated in large multi-pin Burndy ring-locking connectors, and the other opening to reveal a remote control, documentation, three antennas, and one more cable with equally dramatic terminations — closer inspection revealed it was in fact an extremely highly engineered version of a kettle mains lead. This super-kettle-cable (Naim’s Power-Line, to use its proper handle) didn’t, however, directly power the component we were preparing to review, the ND 555; it connected to the CD 555 PS, and from this the pair of thick cables then connected to the ND 555 itself.

Why two cables? Because they deliver separate supplies to the ND 555’s digital section (the inputs through to the DAC) and the analogue sections (the current-to-voltage converter and analogue filter section).

Phew. Naim clearly doesn’t mess around when it comes to power provision.

High 500
But then this is, of course, Naim’s range-topping 500 Series. It offers the best Naim can deliver, ready to play through an amplifier of the level of its NAP 500 amplifier first introduced in 2000, even the extraordinary Naim Statement pre-power introduced in 2014 (and previously featured in these pages). The 500 Series is Naim’s ‘elite’ range and is, to quote the company, “the result of a single-minded pursuit of musical performance with a narrow focus on enhancing the aspects of music that matter to us most: pace, rhythm, timing and ultimately, emotive power.”

Had we been reviewing one of the other two network players recently introduced by Naim — the $9750 NDX 2 or the relatively entry-level $4750 ND5 XS2 — then less portage would have been required for these more conventional components; the 500 Series components take everything to the next level.

Quality plus convenience
All three of the new network music players take the streaming abilities developed for Naim’s popular Mu-so wireless speakers to a new hi-fi level. Yet they share an interesting combination of convenience and quality — there’s Spotify Connect and Chromecast onboard, Bluetooth and AirPlay too, so there are many paths to playback, some of better inherent quality than others.

To experience the best that the ND 555 has to offer, you should play files over your network, using Naim’s app for navigation, or Roon, which is increasingly the discerning audiophile’s control and server software of choice. In this way you can enjoy up to 32-bit/384kHz PCM playback, and up to quad-speed DSD. And when doing so, you won’t be fretting over the many technical innovations and modifications that Naim has packed into the circuits, as described below and by Steve Sells, Naim’s Head of Engineering for Electronics, in our interview overleaf. Instead you’ll simply be loving your music. Because we thought the Naim ND 555 sounded simply thrilling.

Tech fest
So let’s get into that tech. As noted, high-quality power provision is a key priority. In addition to “the best external power supply we’ve ever made”, the ND 555 makes extensive use of Naim’s DR discrete-component voltage regulators, which have a low current draw and promise both lower noise and much faster voltage recovery than the previously used monolithic regulator.

“We have four DR regulators dedicated to powering the DAC,” Steve Sells tells us in our interview (you can read the interview HERE). “These are placed directly under the DAC on a separate PCB. The DAC is sensitive to noise on its power supply and the DR regulator had a dramatic effect on the sound quality.” The DRs also feed the sensitive analogue circuits; there are, in all, 13 of these DR regulators in the NP 555.

Naim highlights also the use of low-voltage differential signalling (LVDS) to route both the digital audio signal and the clock; it says this low-noise, high-speed method minimises timing errors because of its speed and also reduces radiation thanks to its low noise.

And there is a large buffer of RAM onboard, sufficient to store a full five minutes of red-book CD audio to guard against any bottleneck in streaming; Naim nicely calls this a ‘stream-catcher’. 

This allows a new system of master clocking to be employed, with the DAC clock rather than the source governing the rate at which audio data is streamed in. The clock is kept close to the DAC chips and sent to the streaming card again using the high-speed low-noise LVDS signalling. Again Steve Sells goes into more detail on these in our interview linked at the end of this review.

The data is over-sampled at exact multiples to a rather extreme 40-bit accuracy before being fed to the DAC, which is, perhaps surprisingly, a Burr-Brown PCM1704. This is a discontinued DAC; Texas Instruments, which bought Burr-Brown Corporation back in 2000, stopped making them five years ago and had considered them superseded as early as 2004. But Naim considers the PCM1704 to have exceptional sound quality, being a true R2R ladder DAC using repetitive arrangements of precise resistor networks; extremely accurate trimming of the resistors is required to achieve this high performance. Newer delta-sigma DACs are easier to manufacture and may measure better, says Naim, but it considers the PCM1704 to be the best-sounding DAC chip ever made (and specifically uses only the highest-performing PCM1704U-K variant in the ND 555). When production ceased, Naim acquired a stockpile of these DACs while it could, though in order to keep the ND 555 on its books and have enough spares on hand, it admits that this may be the last commercial product ever to use this iconic device.

One potential issue — this type of DAC design won’t handle the continuous one-bit stream of DSD directly, so DSD streams are converted in the ND 555 to PCM by the SHARC DSP. But this is 352.8kHz, 40-bit floating point PCM, later upsampled to 705.6kHz/24-bit for the DAC conversion, and since it is low-pass filtered to remove DSD’s ultrasonic noise, the result might even improve on performance. (That nearly all DSD has been previously converted from PCM anyway is a separate discussion — see our interview with Bricasti’s Brian Zolner in this issue.)

Physical design, both in terms of layout and in terms of construction, is addressed with similar levels of attention to detail. The PCBs are suspended on sprung sub-chassis systems with heavy brass plates (heavy, like several-kilograms-of-brass heavy, which explains much of the weight of the product, the mass delivering a low natural frequency for the six steel-coil springs which support the plate) to minimise the effects of microphony. Steve Sells notes he’s particularly proud of the way the digital circuits have been enclosed within a nested Faraday cage, a six-sided aluminium box within the main enclosure that will protect the analogue circuits from RF emissions, the only holes being small cut-outs where wire connections pass through.

Naim’s ‘next-level’ philosophy for the 500 Series applies even at the retail level, long after the components have left Naim’s UK HQ. “It takes a special level of expertise to properly demonstrate the 500 Series,” says Naim; “all have undergone intensive training to earn the title of 500 Series Specialist”. There are 13 such retailers listed across Australia.

Set-up and listening
We had, thankfully, been pre-advised to remove the transport screws, and we had checked the Quick Start Guide for reference as well, which added the sensible tip not to invert the player while doing this. We made a bridge of it between two boxes so that it didn’t even require tilting.

Then we connected the separate power supply. The first time you connect one of the chunky Burndy connector cables (Burndy is a New Hampshire company which has been in the business of connecting electrical devices since 1924), there is much studying of its geometry to be done before roughly aligning the pins with each other and pushing the plug home, then turning the ring-lock into place with a satisfying click. It takes only a couple of tentative connections before you realise how solid the Burndy system is, and start shoving them home like a pro. All three power cables in place, with the third one given the cleanest possible connection direct to the frankly dubious power supply of Sydney’s North Shore (just the 246.2V coming through on the morning of set-up), we powered up the power supply. The ND 555 also lit up in response, with a fiery colour splash on its five-inch front-panel screen, soon replaced by a monochrome set of source icons.

We waved the wonderfully weighty and stylish aluminium-cased remote control in its direction, not that waving was required, since Naim has moved to Zigbee radio frequency remote control, replacing its traditional infra-red remotes, and removing the need for line-of-sight between the remote handset. Nice, although it didn’t seem to work; none of the keys moved the display selection between the various icons, and none of the stars and squares and rectangles on the remote buttons would coax the front-panel screen into motion. Back to the Guide... oh, you have to pair it, like in the olden days. Hold this button, that button, two Hail Marys and an Abracadabra, and the remote is working.

Now, says the Guide, download the app!

Naim’s apps have been through quite radical deconstruction in recent years. Not long ago our sister publication Sound+Image gave its ‘App of the Year’ award to Naim for a remarkable app which scraped the internet for information on whatever was playing and presented what looked like an on-screen CD booklet with track listings, album and band information (sure you could Google all that, but it was a lovely presentation).

That’s all gone now; perhaps Roon has cornered the market in scraped info, and Naim’s current app is instead rather more utilitarian. This is not a bad thing; it’s fast, solid and reliable — once you’ve mastered the Naim iconography. While that remote control presents just the symbols, which we confess we find less than self-explanatory (unless you’re accustomed to Naim’s quirky track-record of doing things ‘our way’), both the app and the front panel display include text labels to show what’s available. The star means favourites, yes; four squares with one filled means multiroom, natch; a beaming box means internet radio; a box with a down arrow means digital input… Owners will, of course, learn these soon enough.

As mentioned, however, Naim’s app is not the only way to address the ND 555. It’s fully Roon Ready, and popped up immediately in Roon’s audio devices list, ready to be configured. Three times, in fact, since it also appears as a Chromecast and an AirPlay device.) All our listening notes were made using Roon operation; we would have done more with Naim’s app but an output issue curtailed our listening before we got there. But from that week with the ND 555 on Roon, we were already convinced by the performance. At first, when we were A-B switching between this and our favourite but significantly cheaper USB DAC, we had thought it less than dramatically differentiated. On the ‘New Blood’ orchestral version of Peter Gabriel’s Intruder (24/96), there seemed at first very little difference between our reference and the ND 555… until things rose to climax. Then our reference DAC slightly flattened the sound, losing the sense of space around the individual elements, whereas the Naim’s delivery remained entirely three-dimensional and clear.

Them Crooked Vultures’ New Fang is a blistering track which can similarly wall up on lesser gear; the 555 allowed the Kashmir-like left-channel strings to rise above the rhythmic lock between John Paul Jones and Dave Grohl, while the vocal held solid in its own little bullhorn-Elvis world: this is a 21st century Black Dog, and its energy can simply overload and smear all too easily. Not here. Every piece in the whole was kept utterly clear, simultaneously isolated but connected. We’ve never heard it better.

We sampled the new Streisand album ‘Walls’, the ND 555 delivering it lush yet clean, resisting an edginess to her vocal on the title track which our reference DAC had added; things were more natural through the Naim.

By the time we had balled our eyes out at a recent live version of Wild West Hero by Jeff Lynne’s ELO, and then tranced out entirely through Ry Cooder/VH Bhatt’s Ganges River Blues at 24/96, we thought — well yes, maybe there is something different here, something beyond, something which is delivered by the cumulative details to which Naim dedicates its engineering team and time.

We didn’t get to listen quite as long as we’d have liked, but our week with the ND 555 in our system included enough moments of magic that we were entirely convinced by its ability to consistently thrill, by the quality of its conversion, and the extreme efforts at ensuring the results are delivered at the highest, cleanest and lowest-noise levels of performance.

Naim’s second greatest achievement is to bundle this with such ease of use. Via Naim’s own app or using Roon, you can run the many music sources from your phone or tablet, shifting from Tidal to your own tunes, even shouting ‘Hey Google, play Miles Davis on the Naim’ and having your Google device have Chromecast pop the ND 555 into Spotify Connect mode. There’s multiroom operation possible — a ‘party mode’ addresses up to six Naim streaming products under control of the app.

This is not an audiophile-only device. It requires no effort and just a little familiarity (those remote symbols) to operate. It offers everyman ease of operation backed by sensational audio performance. A triumph.

Naim ND 555
Price: ND 555 $25,500;
555 PS DR $13,250

Audio inputs: 2 × optical digital (to 24-bit/96kHz); 1 × coaxial RCA (to 24bit/192kHz); 1 × coaxial BNC (to 24bit/192kHz); 2 ×USB-A; Chromecast built-in; Apple AirPlay; Bluetooth (including aptX HD); UPnP; Roon Ready
App services: Spotify Connect, Tidal, internet radio vTuner premium 5
Format support: WAV to 32-bit/384kHz; FLAC, AIFF, ALAC to 24-bit/384kHz; DSD 64 and 128; MP3, AAC, OGG, WMA, M4A.
Audio outputs: 1 × RCA pair, 1 × 5-pin DIN
Remote control: Zigbee RF4CE (Metal)
Networking: Ethernet (10/100Mbps), Wi-Fi (802.11 b/g/n/ac)
Dimensions (WHD): 432 × 87 × 314mm
Weight: 12.25kg

The accompanying interview with Steve Sells can be read here.