COCKTAIL AUDIO N15D DAC/NETWORK STREAMER
Very compact, very versatile, totally capable and sounds great. But as for its app…
The Cocktail Audio N15D is a compact and very versatile device which can handle more of one’s digital audio needs than most similar devices. And, by ‘compact’ I really do mean compact. This unit is only 180mm wide, 195mm deep and 50mm tall. I kept it on my desk for several weeks and barely even noticed the loss of space.
THE EQUIPMENT
At the front is a power button, a 6.5mm headphone socket, a level control and a
USB port. At the back are:
• a proper 3-pin power socket—the power
supply is in-built
• two hefty RCA sockets for analogue
output
• a coaxial digital audio output
• an optical digital audio output
• two USB 3.0 Type-A ports
• a USB Type-B socket for connecting to a computer so you can use it as a USB Audio device for playback
• an Ethernet connection for streaming
network audio
You can plug in USB mass storage devices—a thumb drive, or USB hard disk or SSD—with music on them for playback, or you can plug in an optional Wi-Fi attachment. The standard unit is wired Ethernet only.
There is also a bay for installing a 2.5-inch hard or solid-state drive. That could be up to four or five terabytes these days. Unfortunately, that does not mean that you can run the unit independently of the network because the only real way to control it is via the network using an app.
The Music X app is available for iOS and Android. You use it with the unit to play music from the disk installed in the unit, from a hard disk or flash memory attached to one or more of the USB ports, from local network resources and from a number of Internet streaming services. Those services are Qobuz, Tidal, Deezer, Napster, HighResAudio and Amazon Music. If your preferred streaming source is Spotify or Google Music sorry, but you’re out of luck.
I was going to add the same with regard to Apple Music, but since the unit also supports Apple Airplay, I guess you can just use the app on your iPhone or iPad. But remember, the music will be coming to your device and then being sent on to the Cocktail Audio N15D, not being fed directly to it from the Internet.
But you can, of course, plug the unit into your computer and use its DAC capabilities to stream from the likes of Spotify.
INSTALLATION
I didn’t spend much time on the computer DAC functionality. The point of a device such as the Cocktail Audio N15D is to provide digital audio without the need to resort to using a computer. But I did plug it into a
Mac. It was instantly recognised and the Mac reported that the unit supports audio up to 384kHz and 24-bits.
The tray to install a hard drive is easy to use. The screws used to secure the drive in the tray are provided. Use them or you’ll have trouble getting the tray back out. I used a 500GB hard drive. After I’d done that I went into the system settings in the app and told it to format the drive—it defaults to the Windows standard NTFS format. That process took around ten seconds. I also plugged a
5TB hard drive into one of the USB 3.0 ports. And of course I plugged the unit into my network. I tried out the Novatron Music X app on both an iPad and a small Android tablet. It worked pretty much identically on both.
If your preferred streaming source is Spotify or Google Music sorry, but you’re out of luck
As is the way of these things, the unit’s firmware is updated from time to time. So after installing it, I went to the relevant bit of the app and had it check via the network. It found an update and asked if I wanted it updated. I did. It took about ninety seconds to download (via NBN). And then the app crashed out. When I fired it up again, it found the unit, but said something about either sending a ‘WOL packet’ or ‘deleting’ it. I had no idea what to do, but deleting it didn’t seem wise so I chose the former. I had to repeat it one or two times—I suspect the unit hadn’t finished rebooting—after which it started up normally.
I relate this because even though I have played with dozens of these devices, I still feel some trepidation during firmware upgrades. What if something goes wrong and the unit is bricked? Also, devices ought to hold one’s hand and not leave one trying to interpret obscure tech messages. The firmware used for this review was N15D-CA-1.0.0.r1454.
THE APP
With great power comes great complexity and not a small amount of confusion (with apologies to Spider-Man). It wasn’t helped by some poor design aspects. The main screen of the app looks clear enough. At the top is Music DB, then Browser, then Playlists, then i-Service. At the bottom is Setup.
The ‘i-service’ item provides access to internet streaming services. I set up Tidal, to which I have a subscription. But it was cumbersome process to do such a simple thing as play a whole album. After selecting Tidal I would drill down through the folder structure to an album. But there was no way of just playing it at that point. I’d have to go into the track list. Then I’d have to tap on a small tick box to the top right of the list.
That caused another small tick box on the other side of the list to appear, as well as a bunch of tick boxes next to the files so that you can choose which ones you want to play. If you want to play the whole album—you know, the kind of thing one generally wants to do—you then have to tap that new tick box, which fills in the boxes next to all the tracks. So how do you then play them? Well, you have to then tap the first tick box again, which pops down a ‘Play’ option.
Which, really, is just about the most difficult way I have ever experienced of simply playing an album.
For several weeks that was also the only way I could play a lot of stuff accessed through the ‘Browser’ menu option, but it unexpectedly reverted to a proper way of working, which was: tap down to the album level, tap the dots next to a folder or album name and choose Play Now.
There are other useful options, such as ‘Add to Last’ to tack it onto the current play queue. A pity you can’t do that with Tidal.
The Browser menu option gives you access to the various drives you have plugged in (or installed), as well as to DLNA/UPnP material on your local network, plus (in theory) to network ‘shares’.
LOADING MUSIC
As I mentioned, I formatted within the unit the hard drive that I installed. How to load music onto the Browser-accessible part of that drive?
Well, you have to go into the settings and enable the Samba file server and change the Workgroup to whatever yours is called. It required a switch off-and-on for that change to take. I spent quite a bit of time trying to get it to work, but it wouldn’t. My Windows computers reported that ‘The remote device or resource won’t accept the connection’.
It also offers an FTP (File Transfer Protocol) interface. I downloaded and installed an
FTP client, and this did indeed work. Slowly, though. It took several hours to copy just 30GB of MP3 files across.
And then, after I’d finished my draft of this review, removed my hard drive, performed a factory reset on the unit and packed it up, I decided to double-check something. And since I was doing that, I tried enabling Samba again, and this time it did work! And that meant I could just drag and drop music from other places on my network onto one of the drives attached to the N15D. However it was pretty slow, running at about 1MB/s. My network speeds are usually up around 60 to 80MB/s. It took about ten minutes to copy across sixteen MQA-encoded files amounting to 674MB.
The unit also has a web interface. That works quite well and shows a nicely formatted list of tracks in the Music DB.
THE MUSIC DB
When using the Browser on attached storage, you just navigate through the file structure.
I could just drag and drop music from other places on my network onto one of the drives attached to the N15D
But the Music DB allows navigating using
ID3 tags in a way similar to DLNA playback.
I imagined that the Music DB would just index the various connected resources, including the internal drive. Using the Browser, you tap on the menu dots next to a music file or folder and select the option to add that file or folder to the Music DB.
But what does it mean to add to the
Music DB? The first hint was when I went to the terabyte or so main music folder of the USB drive. Add to the Music DB I told it. It popped up a message: did I want to copy or move the files? I didn’t want either. I wanted them indexed. At that point I should have cancelled the function. But here’s where the poor app design becomes apparent. You can’t cancel. There was no cancel button. Tapping outside the box on the iPad didn’t make it go away. I could have zapped the app, and perhaps I should have, but a kind of morbid curiosity took hold. What would happen?
I told it to ‘copy’. And then the box changed to a copy dialogue showing the files, one by one, as they copied across to the hidden Music DB section of the internal hard drive. It turned out that, yes, the whole files were being copied across. A typical 200MB DSD file took around five seconds.
It seems that the Cocktail Audio N15D divides the internal hard drive into two portions: one part that’s accessible to the user via the Browser function, and a second, inaccessible part which holds the Music DB music.
As I watched the process unfold, the accessible part of the internal disc kept shrinking. It started at around 450GB in size, and as I write now, several hours later, it’s down to 250GB. The copying speed was around 37GB per hour.
If I have understood this correctly, this does not seem like a good idea. As I said, the music folder I selected has about a terabyte of music in it. That entire disc is only half a terabyte in size so there’s no way that the music will fit. Good design would have had the unit check this before it started and then give some options.
As it is, the process seems uninterruptible. I can find nothing in the app to stop it. When I shut down the app and switch off the iPad, it just continues the copying. In the end, with time pressing, I just had to switch off the unit. Since I was planning on reformatting that drive later, I could take that chance. Then I went through and selected a number of specific folders for importing to the Music DB for use.
While I am complaining about the Music DB, it does index the music it imports and you do have several ways of displaying the music for selection, such as by Artist, Composer, Artist/Album and so on. But you have to pick one of those in Settings. Why aren’t they all available as options in the Music DB screen?
(I later examined what the unit had done with the drive. It had created a new folder, called ‘.DB’ in the root folder of the drive with copies of all the music, plus some artwork it had extracted. The N15D hides that from the user.)
DLNA
The Cocktail Audio N15D worked well with Apple Airplay (it uses a third-party Airplay clone called Shareplay) and it mostly worked well with my usual DLNA player software on my Android tablet. But I could not get that player to stream DSD music to the Cocktail Audio N15D without converting it to PCM. This was most likely something to do with MIME file types (don’t ask). And, of course, it didn’t give access to Internet streaming services.
TEST RESULTS
The Cocktail Audio N15D provides a classic output frequency response: down less than 0.05dB at 20kHz and then a brick wall after that (–6dB at 21.5kHz) with 44.1kHz, 16-bit signals. Using that same digital standard, noise came in at –94.9dB A-weighted, with a fair bit of (measured) noise breakthrough, particularly in the low mid and bass registers. THD was 0.0037%.
With 96kHz, 24-bit signals the unit was again clearly optimised for a flat, extended frequency response. The output was down by 0.5dB at 43.5kHz before hitting the brick wall filter.
The unit is supposed to support audio playback up to 384kHz sampling, and it certainly played those files, but with 192kHz, 24-bit signals something odd became apparent. The output was maintained out to 36kHz (–0.5dB) after which it then fell off rapidly, never getting past the Nyquist frequency for 96kHz sampling. To explore what was going on, I plugged the optical output of the unit into an external DAC. It reported 96kHz sampling. So 192kHz content, at least, is being downsampled to 96kHz.
The noise performance with 24-bit audio was inconsistent and I was unable to isolate a specific cause for the differences.
Essentially, the noise was down either around –95.5dBA or around –110dBA. I presume that somehow noise from the Ethernet connection was getting through, so perhaps there were different noise states in my network during the different measurements. (Why did I not disconnect the Ethernet cable? Because the N15D won’t work without it!) Graph 5 shows two of those measurements, along with a third where I fed the output of the Cocktail Audio N15D to a separate DAC via optical (this gave a result of –116.1dBA). I stress, none of that measured noise was audible, whether via headphones or line output. THD with 24-bit audio was down at 0.0008%.
The unloaded voltage of the headphone output was at 3.67-volts RMS for sine waves modulated to peak at 0dBFS. Into a 295Ω load, that reduced to 3.55-volts, for 42mW output or 16.3dB above headphone sensitivity. Into a 15.9Ω load, the output remained unclipped, but reduced to 2.22-volts due to internal resistance. That works out at 310mW and 24.9dB above headphone sensitivity. Both of those are more than ample.
The voltages I measured put the internal resistance of the N15D at just over 10Ω. That’s higher than I’d like, but the frequency response influence on most headphones should be minimal, especially those with an impedance higher than 32Ω.
LISTENING SESSIONS
I normally put the testing (objective) section of these reviews after the listening section, but I reversed it for this one so I could think and talk about the discrepancy between some marked imperfections in measured performance and my listening.
That’s in large part because, using the Cocktail Audio N15D as my main listening platform for several weeks, I found the listening experience (as opposed to the practical one) to be an utter delight. I fed its line outputs into my audio system, but I mostly listened with headphones, switching between an Oppo PM3 (closed back, and exactly 26Ω right across the audio band), Focal Elear
(open back, 80Ω nominal) and Beyerdynamic Amiron Home (open back, 250Ω nominal). Oh, plus my ancient Sennheiser HD 535 headphones (open back, fairly low sensitivity, 150Ω impedance, varying across frequency band).
First, the Cocktail Audio N15D happily, easily, drove all four sets of headphones to unreasonably high levels. And that includes both of the higher-impedance models. It delivered the sound cleanly with zero audible distortion. I don’t know the impedance curves of the Focal or Beyerdynamic headphones, but the Sennheisers are all over the place. The in-line impedance had no noticeable effect on the frequency balance.
But one word of caution, when you pull out a set of headphones, the unit seems to reset itself to maximum volume. It cuts the level again when you plug in another (or the same) set of headphones, but it takes a second to do so and is thus very loud for that instant, so it’s a good idea to pause the music when switching headphones… or when unplugging and replugging the same pair.
I am inclined to think that that Cocktail Audio N15D imposed no particular character of its own on the sound, leaving it up to the headphones to decide that. But I did have a sense that the Beyerdynamic headphones, which tend to be quite bright, sounded a little smoother, and a little more in check in the treble than usual. There was a slight narrowing in the range of characteristics between the headphones. It was as though the N15D was making each of them be the best headphones they could be.
Genre didn’t matter much. At this moment I’m listening to ELOII through the Focal Elear headphones, but I’ve also been through some early Black Sabbath, much of Elvis Costello’s early catalogue (on Tidal, many of them Master Authenticated), the Muse-like 30 Seconds to Mars, Vladimir Ashkenazy playing Beethoven on Decca, the Schedrin version of Bizet’s ‘Carmen’ on Chandos, and a whole lot more that have escaped my memory. And in every case they sounded—I have to return to that word—delightful.
So how do I reconcile my aural experiences with the measurements I made that were well short of state of the art?
First off, I’d note that what’s going on inside the Cocktail Audio N15D is fairly opaque. How can I tell whether DSD tracks are being decoded natively and converted to PCM and then decoded? As I have demonstrated, it turns out that 192kHz tracks are being converted to 96kHz and I was none the wiser until I noticed the measurement anomaly. The unit does apparently recognise MQA and flashes up an authentication mark and reveals in its ‘Meta Info’ page tracks that it can be unfolded to 352.8kHz, 192kHz or whatever. But does it actually do that? I defy anyone to be able to tell by ear.
But I would argue that the state of audio development in the electronics and digital portions (but not in transducers) has well and truly exceeded the ability of the human ear to discriminate. Once a device delivers a noise floor better than –90dB, high frequency extension to well beyond 20kHz that’s flat across the audible band, along with distortion levels which require at least two decimal points to measure, further improvements will make for nice numbers, but no audible difference to the sound.
Actual audible differences, all of the above being achieved, come from other things, the main one probably being the ability of the output stage to control the transducer.
CONCLUSION
To reiterate, the Cocktail Audio N15D is a compact and very versatile device which can handle more of one’s digital audio needs than most similar devices and will also guarantee you an utterly delightful listening experience no matter what type of headphones you’re using, or what devices you connect to its other outputs. I just hope that that the app can be improved. Stephen Dawson