What is the iFi Audio Zen Blue?
The iFi Zen Blue is a Bluetooth DAC. This is not an unheard of category of product - over the years, I have looked at a few of them - but one that doesn’t tend to produce too many Bluetooth specific devices. It makes more sense to add Bluetooth to a Chord Hugo2 or Auralic Altair G1 as an extra input than it does to produce a device that only does Bluetooth. This means that when we have seen Bluetooth DACs, they’ve been at the more affordable end of the market and this has some unavoidable limitations to how much a manufacturer can cram into them. This is not to say that there haven’t been some impressive engineering efforts over the years. The now departed Mass Fidelity Relay was a very clever (and largely bespoke) piece of kit and was, for many years, about the best implemented Bluetooth device I’d ever tested.
Now, iFi Audio has entered the fray with the Zen Blue. iFi is an interesting company. It produces a wide selection of products (lurking in the range are things with valves and a straightforward take on a BBC broadcast monitor) and some of these products are very clearly a considered take on the perceived best in class and making them better, such as with the very talented xDSD. Others like the Zen Blue are rather more a case of the company setting out to reshape a nascent category of product. The Zen Blue certainly promises the ability to do this but can it actually deliver?
Design & Specification
Bluetooth’s greatest strength is also its greatest weakness (don’t worry, in contrast to some recent content of mine, this will not be an extended and tortuous journey through metaphors). It is an open standard that has become an indispensable part of modern life. Like any open standard though, this leads to a degree of fragmentation. As defined by the standard, Bluetooth must support the SBC audio compression codec for the transfer of audio and that’s it. SBC is easy to use, stable and generally pretty bullet proof.
In many applications, SBC is honestly all you need but it does have some fairly clearly defined limitations for people wanting a bit more from their audio. Into this breach has come solutions but the issue is in the use of ‘solutions’ plural and not one agreed manner of making Bluetooth better. For quite a while, it did look like aptX would become the de-facto high quality Bluetooth standard but it wasn’t to be. Apple’s conflicts with Qualcomm (the creator and license holder of the standard) ensured that the iOS platform has gone its own way and now makes use of AAC Bluetooth.
Then, to make matters more confused, we have even more niche Bluetooth standards like LDAC and HWA (not aware of HWA? Don’t worry, neither was I. It’s Huawei’s proprietary enhanced Bluetooth standard). As if determined to get in on the act, Qualcomm has embarked on a ‘Fifty Shades of aptX’ style program, adding bandwidth and widgets to their baby. In theory, this is great but the reality is that in 2020, you can have a phone or tablet that can notionally perform at a certain level and a receiving device that doesn’t carry that particular flavour of enhanced Bluetooth and means you wind up using SBC anyway.
The reason for this extensive preamble is to set the context into which the Zen Blue arrives. This is nothing less than a sort of ‘Rosetta stone’ of Bluetooth. Making use of Bluetooth 5.0 as the basic carrier, it supports *deep breath*, SBC, AAC, aptX, aptX HD, LDAC and HWA. It’s a mark of the ongoing carnage of Bluetooth standards that even this isn’t quite sufficient as aptX Low Latency and aptX Adaptive are absent but at the moment, I don’t know of any transmitting device that does have them, so the oversight is forgivable and you can delight in revisiting this review in the months and years to come to mock me in the comments if they suddenly become all conquering.
This is nothing less than a sort of ‘Rosetta stone’ of Bluetooth
The decoding is handled by a Qualcomm 5100 series device that is partnered with an ESS Sabre DAC. This isn’t surprising; ESS has pretty much cornered the market by this point but with specific regard to Bluetooth, it’s encouraging because the Sabre is one of the more effective off the shelf solutions for jitter reduction - which is an unavoidable facet of Bluetooth in all its forms. Before any conversion takes place, the signal is tidied up and delivered in the best quality possible.
The output stage is also interesting. It’s fully balanced which is pretty rare at the price and, even more unusually, you can access it in balanced form. The chassis is too small for a pair of XLRs so instead, you get a single 4.4mm socket which performs the same role. This sits alongside a pair of more conventional RCA outputs. These connectors both benefit from some rather impressive niceties such as ‘OV Series’ op amps and TDK Class 1 ceramic capacitors which are impressive things to be lurking in a £130 product. Both of these connections are, as far as the iFi is designed, fixed level. You can adjust the incoming level via the transmitting device but this may involve bit reduction that will affect quality.
Impressively, iFi isn’t done there either. Flick a switch on the rear panel and the Zen Blue switches to a transport. It can be connected to another DAC via optical or coaxial connections and make use of their decoding. This is potentially very handy because if you’ve spend out on a decent decoder already, it doesn’t really matter how good the Zen Blue sounds, you aren’t really going to want to double up on that decoding.
All of this comes wrapped in a compact but well-made chassis. Compared to the dearly departed Mass Fidelity, the iFi doesn’t feel as wonderfully solid but it’s well made and not unattractive. As befits a device with one input, the controls are limited to a single pairing button and a light that shows the sample rate that the Zen Blue is operating at. The most useful aspect of the control isn’t a control at all but is in fact the logo. This changes colour to denote the type of Bluetooth that the Zen Blue is receiving. This sounds inconsequential but it really isn’t. One of the reasons that Bluetooth has descended into the fractured mess it finds itself in is that it can be maddeningly hard to discover what type of Bluetooth your devices have connected at, leading people to believe all is well. iFi has managed to sort this at a stroke.
The Zen Blue itself is attractive enough. I don’t really like the giant aerial but I can’t argue with the performance it offers. The Zen Blue is small enough to be stowed behind another piece of equipment if you don’t want it on display and attractive enough to ensure you won’t mind having it on display. I’d like a black version but can’t really argue with the aesthetic otherwise.
How was the Zen Blue tested?
The Zen Blue has been attached to an IsoTek Evo 3 Aquarius mains conditioner and used via both the analogue and digital outputs. The analogue output has been tested into a Cambridge Audio Edge A Integrated amp running into Kudos Titan 505 standmount speakers and Marantz CR-612 mini system with Spendor A1 speakers. The digital outputs have been tested into the on board digital inputs of the Edge A as well as a Chord Electronics Hugo Mscaler and TT2 DAC combination running into the Edge A. Transmitting equipment has been an iPad Pro (2019 model), Onkyo DP-X1, Sony Xperia XA2 and Essential PH-1 to test AAC, aptX, aptX HD and LDAC respectively. Material used has been Spotify, Tidal and Qobuz with a little bit of testing of content from a Melco N1A using Bubble UPnP.
Find out more: Audio Formats - What Does What and What It All Means
Kicking off testing with the iPad and the Onkyo alternating between content on Qobuz shows that the iFi’s basic implementation is really very good indeed. Switching the Bluetooth off on the connected device and switching the other one sees it connect to the new device quickly and reliably every single time. If this sounds trivial, consider that the combined engineering might and resources of Ford and Sony were absolutely unable to achieve the same thing in my car. Once the iFi has made a connection, it is completely and utterly stable.
From the outset, the performance of the Zen Blue is interesting. In some of the recent tests of Bluetooth headphones, I’ve noted that their voicing and general behaviour is governed by working via Bluetooth and, because a huge chunk of these devices will be iOS devices running AAC Bluetooth, this becomes a sort of de facto ‘it must sound good used this way’ benchmark. This is not the case with the iFi. Moving between the iPad and the venerable Onkyo and listening to the gorgeous Bat for Lashes cover of Boys of Summer on Qobuz reveals that the extra bandwidth of aptX really does make a difference.
Now, for the avoidance of doubt, I regard the Zen Blue as an excellent AAC Bluetooth receiver but it has been geared to sound as good as it possibly can with the best quality incoming signal and this means that the extra bandwidth really counts. The Onkyo finds space to the live performance and a more defined sense of the live venue as a space. It’s a reflection that Apple is still rather more interested in AirPlay than it is Bluetooth.
And the better the flavour of Bluetooth you give it, the better the iFi gets. The Sony Xperia is equipped with aptX HD (technically, so is the Essential but that would mean disabling the LDAC connection that I have no other means of testing) and the jump in performance is not small. I’ve remarked in the past that aptX HD is the point where Bluetooth stops being a convenience feature and starts to become more significant. What the Zen Blue does is deliver this in a manner that really allows it to shine. Jack Savoretti’s Dreamers is rich, weighty and entirely believable. Play the same track back via SOtM SMS200 Neo into the Cambridge Audio via Roon and it is better but the differences are detail ones.
And if you have an LDAC source, there is a little more to be had from the iFi. The tonal realism and three dimensionality of the Savoretti album takes another little step forward. Some (very) bold claims are made about LDAC and some of them don’t seem to be borne out in reality but I will say that with the Essential sending the signal to the iFi and it connected to the Edge A via coaxial, those comparisons to Roon become something I would not make the call on in a blind test.
iFi has built the best Bluetooth interface I’ve ever seen and they only want £130 for it.
And those digital outputs are the iFi’s secret weapon. The performance via the analogue outputs is very good - you could argue unreasonably good for something that costs £130 - but it’s these digital outputs that make a good product a great one. Both the Cambridge Audio Edge A and Hugo TT2 have Bluetooth implementations - and in the case of the Cambridge Audio in particular, good ones too. Neither support LDAC though (and realistically, neither will they) so the ability to send their excellent decoding, a stream from an LDAC source means you can get some incredible results. To be clear, I do not think that many people will create a digital source comprising a phone, £130 Bluetooth transport and £7,500 worth of upscaler and DAC… but the performance you can obtain might surprise a few people.
- Truly outstanding Bluetooth integration
- Excellent audio performance
- Superb value for money
- Doesn't have every version of aptX
- Slightly quirky looks
iFi Audio Zen Blue Bluetooth DAC Review
I don’t know how many people on AVForums, let alone the wider audio community, are ‘serious’ Bluetooth users but I do know that there is a subset of people who have ignored the shaky, SBC dependent beginnings of the format and know that some truly excellent results are possible. What the Zen Blue does is remove some of the lottery of getting those results. A device that will make a rock solid connection, automatically choosing the best standard available is exactly what this somewhat confused market needed. iFi has built the best Bluetooth interface I’ve ever seen and they only want £130 for it. The result is unquestionably a Best Buy.
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