Aqua LinQ Network Interface

Review sample supplied by Hexagon Audio
Retail prices in the NL including 21% VAT:
LinQ including one UPnP/DLNA or ROON module: 5.680 euro
Extra module: 1.280 euro
AQlink I2S cable with Ethercon (for La Scala and Formula DAC): 365 euro
AQlink I2S cable with RJ45 (for La Voce DAC): 335 euro

Technical

The Aqua LinQ is a Network Interface that was created following the company’s philosophy of providing only proprietary solutions in a fully modular setup. Further, the LinQ offers four slots that can be used for any combination of interface boards that plug into a connector on the base platform of the device. Available right now are the Roon Ready (RAAT) module and the UPnP DLNA streaming module and these have been fitted to my review sample. Each module’s communication line with the network is galvanically isolated, each module has its own dedicated power supply and in addition, this architecture allows future updates to be fitted very easily. Aqua does not use off the shelf solutions and that policy extends even to the fully-floating hybrid 2-stage Network LAN switch module. In addition to being fit for purpose, this proprietary network switch offers additional isolation and is said to be an important aspect of the LinQ’s performance.

Aqua also makes a point of having made a very conscious decision not to use USB for the LinQ in their quest to achieve the best sound. The output is on AQlink, the aqua I2S proprietary connection. This way, the extra USB interface is skipped to avoid any losses in sound quality. Furthermore, proprietary circuits have been developed in the output FPGA, to implement S/PDIF, AES/EBU and dual-AES outputs. S/PDIF is available on cinch and BNC and all outputs, AQlink included, can be used simultaneously. Depending on the selected output the maximum resolution is PCM 24 bit 384kHz / DSD128.

First use

At the time of review, no manual was available but as it turned out the LinQ works super-intuitively. The unit starts up very quickly and self-initializes without the need to select anything except for the desired Network Protocol, call it the “input”. Some network players have proven to be quite finicky in use and some won’t connect to the network unless they have been booted in a particular mode or have been connected in a certain order. Not so the LinQ. The unit works flawlessly irrespective of starting up with a network cable connected or said cable attached after the unit was already on. Attach it and within seconds the unit connects and is ready to go. It’s exactly as you would expect a network device to work but which sadly is not always the reality.

Make sure not to use any Aqua component directly on another Aqua component or other delicate surfaces. My go-to solution is to use Neoprene pads made by Artesania.

Running In

The LinQ is said to be fully on song after about 100 hours of use. Even so, of course, I listened to it right after having connected it and all I can say is that it impressed right from the start. At the moment of writing, the unit has been in use for about two weeks and has easily had over 100 hours of use but I can’t say that it changed noticeably. Your mileage may vary but to me, it sounded superb right from the start and it still sounds superb after two weeks of use.

Outputs

All the LinQ’s outputs can be used simultaneously and having done this while comparing them I can report that AES/EBU, coax and BNC all sound very, very similar and what little discernible difference can be heard can likely be attributed to the cables that were used. Although the difference should theoretically be audible throughout the spectrum, they are easiest to hear in the upper bass where I can differentiate between coax on Belden RG59 and AES/EBU on Mogami neglex 3080 by the former sounding slightly fuller and the latter sounding slightly more nimble and articulate.

For digital connections in general, I have long preferred coaxial S/PDIF (using Belden RG59 cable) over AES/EBU but, as always, the quality of the connection much depends on the cables that are used as well as the interface implementation on both ends. With my current CH system, as well as the Aqua components, I prefer AES/EBU (using Mogami neglex 3080 cable) for its slightly more precise sound and it is this connection that I used predominantly with the CH Precision C1 DAC for the purpose of this review. As it happens due to the lack of an official standard, many manufacturers choose their own interface for I2S connections. Aqua has opted for RJ45 (the network cable connector) and CH Precision has its own proprietary digital interface which is not compatible with AQlink (or any I2S connection scheme for that matter) which is why I used AES/EBU. Where the Formula xHD DAC was used, AQlink was the preferred method of connection. In the AQlink section further below you can read about the audible differences between the various outputs.

Eagle-eyed readers will discern the La Diva CD transport on top of the Aqua stack. For the purpose of this review, I opted to focus only on the LinQ. In another review, I will elaborate on comparisons between the CD transport and the LinQ network transport.

Listening

The LinQ review sample contains both Roon and UPnP modules but given the overwhelming popularity of the former, I will start my assessments with the Antipodes CX server in Roon mode and will focus on this for the most part.

Starting with the obvious pairing made in heaven, the LinQ was first used with the Aqua Formula xHD DAC, its output relayed very transparently via the Audio GD Master 1 preamp to the CH Precision A1.5 power amplifier that was used with either Martin Logan ESL15A or Magico S1 MkII speakers. All power cables are Belden with Bals schuko and Oyaide C-004 IEC connectors.

Right from the start, the LinQ presents itself as a super-transparent interface. The unit simply never imposes itself onto the signal and what comes out is nothing but the pure and natural music signal, 100% unaltered.

If an audio component has no character of its own, how do you describe it? I will start by listing what it does not do. Firstly, the LinQ performs no resampling or processing of any kind, which I think is always the best you can do in the digital domain. Further, it never puts a restraint on the speed, PRaT or dynamics. It is 100% transparent but never clinical, mechanical or synthetic and it does not change the timbre. Finally, it does not alter the dimensional cues that are embedded in the source signal meaning that small-scale and intimate recordings or grande, room-filling recordings sound just as they should. But in reading this back to myself, I feel that all this does not really describe just how fabulous the LinQ really is.

Comparisons

In order to more clearly expose the LinQ’s greatness, let’s perform some comparisons, starting with perhaps the most illustrative one: the CH Precision C1 DAC. Besides functioning as a DAC, the C1 also offers modularity similar to that of the LinQ and it, too, contains a Roon Ready module. This makes it possible to compare the Roon performance from the same source either via the LinQ and its AES/EBU output or directly into the C1’s Roon Ready module. Normally, I use a direct Pink Faun Digital Link ethernet connection between the Antipodes CX music server but in order to create equal circumstances, I connected all devices using the same OEM CAT6 ethernet cable types directly to the same network switch, which is a very standard Cisco Linksys model. This way, the CX feeds the C1 and the LinQ via the exact same route.

CH Precision C1

In earlier comparisons with USB connections the C1’s Roon Ready network module always provided the best result. To be honest, I fully anticipated this method to also have advantages over, what is in essence, a detour via the LinQ and an AES/EBU interface on two ends. Imagine my surprise when I found that the LinQ’s output sounded spectacularly good. The LinQ’s presentation is a little different from the C1 board’s and I’m not sure which is objectively better. What I can say is that the LinQ’s slightly crispier presentation was highly seductive.

As it turned out, my preference for one or the other mosty depended on which connection I just listened to for a while. On the one hand, the C1’s direct connection via the Roon Ready module has a slightly smoother and more relaxed feel to it. On the other hand, the LinQ counters with a relatively slightly slenderer but also tighter and more expressive delivery. Coming from the C1’s Roon Ready module, the LinQ sounds a little more concrete and upfront. Vice versa, the C1 sounds a little smoother. Depending on system synergy and personal taste, it could swing either way. But even if you could regard the outcome at this stage as a tie that is still a remarkable achievement for the LinQ.

Given that the C1’s Roon Ready module is internally connected via I2S, one would assume that it has an inherent advantage over the LinQ which outputs via the AES/EBU interface where the clock has to be retrieved from the input stream. Whereas I2S over AQlink to the Formula xHD DAC did indeed enable a deeper soundstage with better 3D layering (more details below), I found the differences in this field via the C1 to be vanishingly small.

I would say that the only possible conclusion for the LinQ’s more articulate and concrete delivery in spite of a detour via another digital interface format is that it must be the result of the great attention paid to the network input and the isolation between its connections as well as a splendidly implemented FPGA output section. That, and of course the C1’s digital input section is nothing to sneeze at either.

Reassuringly, where increases in expression can often be accompanied by a decrease in the naturalness and the flow of the music, all that the LinQ seems to do is more clearly relay whatever is in the recordings. The better articulation leads to a crispier sound but it stays absolutely natural and never comes across as technical.

AQlink

Aqua makes a big deal of using I2S on their proprietary AQlink connection as the preferred method and this is with very good reason. Rather than the more common connection methods, I2S does not mix clock and music signals but transports them separately. The big advantage is that the receiving device does not need to extract the clock from the music signal (which can introduce jitter) but is handed the two signals as unscathed as they can be when transported over a cable.

When comparing AES/EBU to AQlink connections between the LinQ and the Formula xHD, the latter connection’s benefits are audible even when using a simple but short 1-meter generic CAT5 network cable. The benefits include a brisker rhythm, crisper transients and an increase in soundstage depth. The latter manifests itself not only as a generic deeper ambiance but also allows sounds to originate from, or disappear into, a deeper position within the soundstage. There is more movement and life in the soundstage, it’s less static. This has the very meaningful benefit of making the performance sound more enveloping and thus more involving. However, when using this generic RJ45 network cable, the bass was also slightly less forceful than with either the AES/EBU or coaxial connections. Because of this, between these cables at this point, it was a bit of a tradeoff between a clearer yet slightly leaner delivery with a more 3D presentation versus a more solid and forceful one albeit with a flatter presentation. Interestingly, an intrinsically better but longer 3-meter generic CAT6 network cable did not always work reliably which only goes to show how delicate the digital signals are. But so far I was using standard ethernet cables. What about Aqua’s very own AQlink cable?

AQlink Cable

Upon changing the generic CAT5 cable for the AQlink cable the difference was astonishing and within seconds, this cable’s supremacy was established. The bass firmed up further but also became more impactful to the point where it was every bit as full and solid as the AES/EBU connection while retaining all the fluidity, 3D-soundstaging and clarity that I noted using the standard CAT5 cable. Clearly, the generic network cable did leave a portion of the signal behind which leads to arbitrary and system-dependent benefits but with the AQlink cable, there was no question about which connection sounded best.

At 365 euro, the cable may not be a no-brainer but a quick look at the high-end competition shows that it is actually decently priced. Similar results might be possible using a cheaper cable but none that I have in my inventory actually did the trick. To be honest, if you can spare the extra cost, I would not think twice and just go with what Aqua has already confirmed works best and order an AQlink cable along with the LinQ.

UPnP

So far, I’ve only looked at the LinQ’s performance using Roon and I’ll admit to almost having forgotten to also test its UPnP section. Inside the LinQ are two separate modules, each optimized for its specific task. A benefit of this, apart from sound quality reasons, is that you can actually send UPnP and Roon streams to the LinQ simultaneously! This makes it simple to play the same track on two systems and simply switch between them using the LinQ’s front panel switches. The signal switches instantaneously and both streams keep working flawlessly.

Just fast enough to allow me to do my work, my regular Windows tower computer is nothing special and it certainly is not audiophile. Long ago I have tried to elevate its performance as much as I could, first using special internal sound cards and particular cables, then external sound cards, USB interfaces, streaming endpoints etcetera, only to find that the AudioAanZee Ultra Flow Music Server connected to the DAC via USB surpassed it with ease. Ever since, I have not bothered using this computer except for the occasion where I reviewed the JPLAY Femto software in the Genelec 8050 computer audio system that I had at that time.

Just because the Antipodes CX server has no UPnP/DLNA server installed by default (it does function as an endpoint), I just used jRiver Media Center on the computer for a quick check, just to see if it worked. Oh, work it did, and more than that!

I had to double-check my findings as I almost could not believe it but sure enough, UPnP performed a little better. I’ll let that sink in. Yes, it was better in terms of being crispier and more resolute and just more “alive”. Roon, on the other hand, sounded fuller but also slightly less precise, a little thickened and dynamically more damped.

The LinQ keeps surprising me. First, it manages to sound just as good as the built-in, I2S-connected, CH Precision Roon Ready board, and now, apparently, now it has elevated the standard Windows computer to sound like an audiophile NAS. Does this mean that all those people claiming that the hardware should not matter as long as the bits come across actually have a point? Well yes, in an ideal world. As I vividly recall this very same Windows computer to sound ill-defined, bloated and even artificial in all earlier comparisons, I actually think that the LinQ and its network isolation play a vital part in this particular outcome.

Qobuz

A comparison using Qobuz (Studio Quality subscription) to stream music from within Roon as installed on the Antipodes CX or directly to the LinQ further confirmed the above. There is no way around it: Qobuz sounds just a bit crispier and better-focused as well as more 3D when playing directly to the LinQ using the Android Bubble UPnP app. Moreover, directly into the LinQ, it sounds much more like local playback than I remember it did when I tried it with different hardware years ago.

That leaves only the question of what causes the differences as noted. Are these caused by Roon or Antipodes?

Music Server / playback application

In order to get to the bottom of the differences in presentation as noted above between Roon on the Antipodes CX and jRiver on the Windows computer, I decided that the easiest way to settle this was to disable the Roon core on the Antipodes CX and enabling it on the Windows computer. This way, both applications are running on the same computer and because the LinQ can accept both streams at the same time it was very easy to switch between the two to assess the differences.

Well, that matter was settled very quickly and in favor of UPnP via jRiver. Indeed, Roon sounded slightly less crispy and direct, less “alive” than UPnP via jRiver. That Roon was now running on entirely different hardware seemed to have made no difference at all which is another testament to the LinQ’s greatness. But, in spite of the LinQ’s immense transparency to show the essence of the music and its ability to raise the quality of upstream sources to a uniformly high level, the music server program still has a small difference on the end result.

Conclusion

Never before has a digital interface, network or otherwise, behaved so utterly consistently and dependently. The LinQ has the uncanny ability to improve the quality of upstream components but it does this while refraining from imposing any discernible character onto the proceedings. Whether using UPnP or Roon and even independently from the hardware that is used upstream, the LinQ always delivers the best possible rendition.

In my opinion, the Aqua LinQ is nothing less than a milestone product. It is the absolute best network endpoint that I have heard and I enthusiastically recommend an audition.

While 5.680 euros is not exactly chump change, the reality is that I can name several competing products that cost multiples. But also think of it this way: any money spent on the LinQ does not need to be spent on any extravagant upstream hardware.

Associated Equipment

Distributor for the NL/Belgium: Hexagon Audio
Manufacturer’s website: aquahifi.com

Read Also

Aqua Formula xHD DAC
Aqua Formula xHD v2 Output Board upgrade
Aqua La Scala mkII DAC