Naim NDX 2 network player

Okay, it’s time to go high-end. The Naim NDX 2 Network Player is for those prepared to spend serious amounts of money for a source component in their high-fidelity setup. With a price comparable to that of a respectable second-hand car, let’s see what you get.

In short

• The Naim NDX 2 network player is not only a network player, it’s also a first class DAC and Bluetooth receiver
• Built in Salisbury, England
• 2 x optical digital audio inputs, 2 x coaxial digital audio inputs (1 x RCA, 1 x BNC), 2 x USB Type A (for connecting USB drives), 1 x Ethernet, Dual-band Wi-Fi up to 802.11 AC, Bluetooth (with aptX HD)
• 2 x analogue stereo line outputs (1 x stereo RCA, 1 x DIN)
• Spotify, TIDAL and Qobuz streaming services; Roon ready
• DLNA/UPnP; Apple AirPlay; Chromecast
• WAV, FLAC, AIFF and ALAC support up to 24-bit, 384kHz, DSD64 and DSD128, plus the usual lossy formats
• Colour 12.7cm screen
• RF remote included
• Naim app for Android and iOS
• Powered by regular IEC 230-volt connection, but provision included for upping performance with external Naim power supply
• 432mm wide by 87mm tall by 314mm deep
• 3 kilograms
• The Naim NDX 2 is a digital audio source device for streaming and DAC duties with an extraordinary build quality, absolutely first class sound, and top notch usability.
• Price: $13,300
• Available at fine high fidelity retail outlets, and direct from distributor's retail division (Naim NDX 2 network player)

More about the Naim NDX 2

What to think of the Naim NDX 2? I think of it as taking the networking and such capabilities from the lovely little Naim Uniti Atom (Naim Uniti Atom review) and attaching it to a no-holds-barred high-end DAC and analogue section. The digital signal handling capabilities are much the same as the Atom, and it looks to me that the display screen on the front of the unit is almost identical.

But the Naim NDX 2 is a proper high-fidelity component in width, and quite apart from the internal features, it also obviously differs in having outside antennae for the dual-band Wi-Fi, plus an extra antenna for Bluetooth. It is extremely solidly built. I think you could stand on it if you wanted and inflict no damage. I suspect much of the ten-plus-kilogram weight is in the chassis and case. As always, while I must stress that the fact that a component is solidly built and heavy proves nothing, these factors remain decent proxies for performance, since they show that the maker has gone above and beyond in at least one obvious element of construction.

The Naim NDX 2 has single-ended line-level outputs. These are available in standard RCA form, and also as a 5-pin DIN which works well with Naim pre-amplifiers which feature such inputs.

While marketed primarily as a network streamer, the Naim NDX 2 also features and excellent DAC stage (no, not ESS and not AKM, but based around the Burr-Brown PCM1792A DAC chip). As high-end manufacturers typically acknowledge, the particular DAC chip is only a part of the process by which great sound is generated. The surround circuitry – quality and design – is just as important. Which is where the Naim NDX 2 comes into its own. Not least of the things the Naim NDX 2 does is re-clock everything, which should pretty much eliminate jitter.

If you want even more from the Naim NDX 2, you can disconnect the power cable and instead attach an external power supply, the Naim XPR DR or the Naim 555 PS.

Setting up the Naim NDX 2 network player

A word of advice: don’t follow the example of this reviewer. It all seemed pretty obvious after all. Since this unit was going into my main system, I decided to use an existing Ethernet connection, rather than load up – possibly overload – my office’s Wi-Fi bandwidth with streaming music (especially as I also had the Naim Uniti Atom connected via Wi-Fi). So, RCA outputs to pre-amp, CD, TV and digital radio tuner digital outputs to the Naim NDX 2’s digital inputs, Ethernet cable plugged in, then power cable. And … nothing much. The unit showed up on the Naim app on the iPad, but the unit itself did nothing except lazily pulse the green ring around the standby button.

So I did what I should have done first: I read the brief quick start guide, which clearly told me to connect the “Burndy link plug to the back of the unit”. That was a chunky black cylinder with the complicated arrangement of pins at one end that had been in the box. It seems that this needs to go into the connector for the optional external power supply. I suppose it either informs the unit to use the regular mains input for power, or it routes that mains power through the plug.

So I unplugged the power cable, plugged in the link plug, plugged the power back in and everything worked smoothly thereafter. The unit tells you how to pair the RF remote control – that takes a couple of seconds – then checked for a firmware update. One was available, so it spent five minutes downloading and installing that. Then, using the Naim app, I followed the steps to complete setup. That involved choosing country and then from a somewhat quirky collection of regions within that county (in Australia’s case there is Eucla and Lindeman and Currie and Lord Howe and Macquarie base in Antarctica, but not Canberra). Then a name for the unit – the unit’s own identifier or a room or a custom name if you prefer – some Google Chromecast stuff and then whether you want to use it as a UPnP server, allowing it to serve up music from a plugged-in USB drive. And that was it.

So I turned on the digital tuner, set my preamplifier to the appropriate input and was met with silence. I cycled through the digital inputs on the Naim, thinking I’d gotten the wrong one. Silence. I fired up TIDAL within the Naim app and set some music to play on the NDX 2. Silence.

I checked the quick start guide again. Ah, it said to connect the DIN output to a preamplifier. I wasn’t using a Naim preamp, and in any case didn’t have a DIN cable. I was using RCA interconnects. So maybe, just maybe … yes, there it was in the app’s Settings/Output Settings. I could set the audio output to DIN, RCA, both or digital only. It defaulted to DIN.

It would probably be a good idea to have the setup wizard ask this question. Or perhaps have the default set to “DIN+RCA”.

Anyway, tapping on RCA instantly had music flowing from the system.

Listening with the Naim NDX 2 network player

Playback equipment:

• Schiit Audio Freya S preamplifier
• Schiit Audio Vidar power amplifier (Schiit Audio Vidar review)
• Lenehan Audio pure copper ribbon speaker cables with gold-plated spade lugs
• Dynaudio Contour 20i loudspeakers (Dynaudio Contour 20i review)

As I discovered when using the Naim Uniti Atom, the first element of fine listening was properly provided by the Naim NDX 2: it was reliable and easy to use. I hate it when I have to spend valuable listening time solving playback problems. Well, there was none of that here. The unit was rock solid. The network connection was rock solid. The whole system was simply a delight in use.

Now, I’m going to say something that in some quarters may be a little controversial. That is that a high-fidelity component cannot add anything to the sound of the source music to make it sound “better”. The best equipment simply refrains from making the source sound worse than it might otherwise be. That is, the best equipment is utterly transparent. It just reveals what’s there.

And if a few decades of reviewing stuff gives me any authority on this matter, may I simply say that the Naim NDX 2 network player was utterly transparent.

An example. Normally I don’t go to something like this for critical listening, but I fluked this one in. “This” in this case is a playlist I created a while back which gathered together, in the correct order, one of the first albums that I ever owned. It must have been a gift when I was a very early teen, or perhaps even a little older. Discogs tells me that “20 Dynamic Hits” was released in 1970 (I was twelve years old for most of that year). It contains things like a Gene Pierson’s psychedelic version of Four Tops’ “Reach Out”, Blue Mink’s “Melting Pot”, the lyrics of which would have the group instantly cancelled these days, the original “Raindrops Keep Falling on my Head” by B.J. Thomas, not the Johnny Farnham cover. Amongst other things it introduced me to Janis Joplin and Blood, Sweat & Tears.

The playlist is in TIDAL (and thus lossless) and I managed to find about three quarters of the tracks, most of which are in proper stereo. I’d been running in the Naim NDX 2 for a while, and again I was just using it for background music while I was doing something else. And this time I set it to playing that playlist. And after a while I stopped what I was doing and started paying attention. The system was now giving an extraordinary look into those tracks. Sure, they’d all been recorded, mixed and mastered on studio equipment that we’d now regard as quite primitive. Most of them would have employed four tracks. Some of the microphones would have been of indifferent quality. Yet, the system was revealing the life within them along with all the defects. Drums were lively, sprightly. And with surprising coherence. Voices had plenty of higher frequencies, without any sense of harshness (except for those few moments of excessive dynamic compression or overloading of the microphone). The stereo spread was reasonable (by 1969/1970 the excesses of the early stereo period had largely been discontinued) and stable.

For many years I’d mentally written off that early stuff as unlistenable. But over the past few years I’ve become acquainted with extraordinary jazz recordings from as far back as the 1950s. And listening to this TIDAL playlist made me realise that my hesitancy has been informed by poor vinyl pressings, often as not somewhat damaged by playback equipment.

With quality audio, streamed from TIDAL, or from my NAS, or from a USB drive I had plugged into the front USB socket (there’s one on the back, too, for a tidier look), the sound was simply as good as I have ever experienced.

And character? Transparency was the character of the Naim NDX 2. It was obvious, from the moment I set it playing from my network attached storage, that the 1986 CD release of Rodriguez’s Cold Fact was a transfer from vinyl, while the problematic 2005 CD version and the excellent 2008 CD version had come from master tapes. With this and with a dozen other albums the NDX 2 simply disappeared. Instead, there was only the music.

Some measurements

As always, it’s worth running some objective tests, if only to make sure that I’m not completely fooling myself. The test files were on my network attached storage rather than feeding them in via one of the digital inputs. One of the results turned out to be quite intriguing.

So, first, frequency response. Here’s the response when the unit was fed a 44.1kHz, 16-bit signal:

As you can see, this is a well-behaved performance. Clearly Naim has chosen a filter with a gentle roll-off rather than gone for a hard brick wall up near 22kHz. The tiny diminution at 20kHz –down by around 0.6dB – is completely inaudible even by the sharpest ears. Notice, too, the near perfect channel balance: less than 0.05dB variation in all of these tests. And some of that is probably in the measurement gear.

Here’s the response with a 96kHz, 24-bit test signal:

Again, Naim has chosen a “slow” filter which, for all intents and purposes, completely eliminates any output beyond 30kHz. At 20kHz the output is down by 1dB, or slightly more than it is with the 44.1kHz test signal.

Finally, we repeat with a 192kHz, 24-bit test signal:

This is very similar to the output with 96kHz sampling, although the level is very slightly higher at 20kHz (-0.8dB). Again, there’s nothing above 30kHz.

I found that result quite surprising, so I ran that test twice, and in between the two tests I repeated it with a high quality digital audio player with its output filter set to “fast”. Its measured response extended all the way out to 90kHz. (I do that kind of thing to make sure that I haven’t messed up with my measurement rig.)

This led to a bit more research which ended up confusing me. Naim says that it uses the Burr-Brown PCM1792A DAC chip, but implemented its own digital filters. So Naim clearly intended this kind of output. Not surprisingly, because audiophiles in general tend to prefer slower roll-off filters. That wasn’t what was confusing. It was the PCM1792A chip itself. I looked up its specification sheet (PDF), and it turns out to support a maximum sampling frequency of 192kHz, whereas Naim has specified the NDX 2 to 384kHz, and I indeed confirmed that it supports such files. Maybe they used a couple of chips.

Noise with 16-bit audio was about as good as it gets: -98.5dB A-weighted. Here’s what that looked like across the frequency spectrum:

Again with the noise, this time with 24-bit audio. It came in at a nicely low -117dBA and looked like this:

Note, both of these noise measurements were with Ethernet connected, not via Wi-Fi. Ethernet is incredibly noisy, and there’s a lot of network gear around which allows this noise to leak into its analogue outputs. There’s not the slightest hint of that here. In other words, Naim has properly isolated those connections from the analogue output circuitry.

You can check out the distortion figures – 0.0005% or lower for THD, 0.004% or lower for Intermodulation Distortion – in this table:

Conclusion

The Naim NDX 2 network player does everything right. It offers broad support for a wide range of sources and audio formats. It sounds great. Its app is highly effective and utterly reliable, which means that the unit is easy to use.

If you’re of the view that you can hear the miniscule amount (if any) of the 40kHz content in high resolution music, or you’re particularly keen on the MQA format that can provide high resolution from TIDAL – not supported by this unit – then you might prefer some other player. But for the rest, just go to a Naim retailer and have a listen and a play, and I think you’ll be convinced.