iFi audio ZEN Blue

General Information

First of a new range of audio components priced at just £129, US$129 and €149, iFi’s ZEN Blue delivers hi-res Bluetooth streaming to any audio system

Southport, England – iFi kicks off a new range of high-quality, super-affordable, desktop-sized audio products with the ZEN Blue – the world’s first Bluetooth receiver supporting all the latest hi-res codecs for the best-quality music streaming from smartphones, tablets, PCs and Macs to any audio system.

The ZEN Blue immediately impresses with its sturdy aluminium enclosure, unusual at such a low price. But what really sets it apart is the circuitry within – as always, iFi has gone to great lengths to ensure that sound quality over Bluetooth is the best it can be, even if it has to be designed from the ground up.

Bluetooth reception represents a mere convenience for many audio manufacturers, enabled in the simplest and cheapest way to ‘tick a box’ on the features list. But the manner in which Bluetooth is implemented – the quality of signal processing and the circuitry that surrounds it – has a big impact on performance. Not all Bluetooth sounds the same, and iFi engineers its products to obtain the best possible performance from every audio source – Bluetooth streaming included.

With the ZEN Blue, this starts with a state-of-the-art Qualcomm QCC5100 chip to process the incoming data – the ZEN Blue is the first product of its kind to benefit from this new-generation Bluetooth IC.

All the latest 24-bit-capable Bluetooth audio formats are supported, including Qualcomm’s aptX Adaptive and aptX HD, Sony’s LDAC and Huawei’s HWA – no other Bluetooth streamer boasts this cutting-edge hi-res specification. Other codecs covered include regular aptX and aptX Low Latency, AAC (the favoured format of Apple iOS devices) and SBC (the ‘plain vanilla’ Bluetooth codec). This means that every possible source device is covered at the highest audio resolution its Bluetooth specification allows.

The Qualcomm QCC5100 offers a ‘system-on-a-chip’ Bluetooth solution, with all functions covered including D-to-A conversion. Many manufacturers would simply rely on this chip to deliver the DAC function, but this is not the iFi way. The ZEN Blue has separate digital and analogue stages; to feed the analogue stage, the processed digital signal is routed from the QCC5100 to a specialised DAC chip from ESS Technology’s Sabre family to convert the signal from digital to analogue.

One of the key advantages of the ESS Sabre DAC chip is its Hyperstream architecture with integrated Time Domain Jitter Eliminator, which helps to deliver vanishingly low distortion and high dynamic range. iFi has found that this allies perfectly with the Qualcomm chip to deliver Bluetooth audio that sounds far better than the norm.

None of this would mean much if the rest of the ZEN Blue’s circuitry were not up to scratch. This is the first iFi product to benefit from the input of legendary audio designer John Curl, who has teamed up with the iFi electronics design team, led by Technical Director Thorsten Loesch, to ensure the circuit design of every product is fully optimised.

The ZEN Blue’s analogue output stage is a balanced design – highly unusual in a DAC anywhere near this price point. It incorporates a range of high-quality circuit components, carefully selected for their performance in an audio context, including professional-grade balanced line drivers, C0G capacitors from TDK and a precision low-noise power supply IC from Texas Instruments. It all adds up to a highly affordable Bluetooth streamer with a sound that punches well above its weight.

It’s all connected

The ZEN Blue adds high-quality Bluetooth reception to any audio system via analogue or digital cable connections. A switch at the back dictates how the digital signal is routed; either through the DAC and analogue output stage, or directly to the digital outputs. On the analogue side, RCA stereo outputs allow connection to amplifiers, active speakers and the like, while a 4.4mm Pentaconn output enables balanced signal transfer to amps/speakers equipped with a balanced input – either a 4.4mm input, or XLR inputs via a 4.4mm-to-XLR cable. For digital connections, optical and coaxial outputs are provided – these allow connection to anything with a built-in DAC and corresponding digital input, such as an AV amp or an external hi-fi DAC.

The ZEN Blue ‘remembers’ up to seven paired Bluetooth source devices, making it easy to switch from one device to another, with impressive reception range thanks to the latest Bluetooth 5 specification. The DAC stage handles sampling rates well in excess of the maximum delivered by current hi-res Bluetooth formats – of the 24-bit-capable codecs, aptX Adaptive and aptX HD support up to 48kHz, while LDAC and HWA reach 96kHz.

The LED at the centre of the ZEN Blue’s front panel changes colour to identify the Bluetooth codec being received, while another LED to the right indicates the sample rate. Qualcomm’s QCC5100 chip can be updated over-the-air, enabling future Bluetooth codecs to be added to the ZEN Blue’s specification.

Find your ZEN

Available from October, the ZEN Blue hi-res Bluetooth streamer is the first of a range of ZEN Series products, all of which share the same 158x35x100mm (WxHxD) aluminium case. It will be followed swiftly by the ZEN DAC, which swaps Bluetooth reception for a USB input and adds an integrated headphone amp. Further ZEN Series products will arrive in the coming months.


Latest reviews

Pros: Great sound
Ease of use
Cons: Bluetooth input only
iFi decided to present an unusual combination of Bluetooth streamer and DAC in one. From the outside Zen Blue looks almost the same as already reviewed Zen DAC. It means that the body is completely made of thick aluminium and feels reassuringly sturdy. Front and back plate have brushed finish, while the rest of its curved body is painted gray. Zen Blue doesn’t possess a headphone amp however.

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Unusual part comes in when you find out that Bluetooth is the only digital input available on this unit. Yes, you heard it correctly, there is no USB or any other physical way to connect it to the source. Situation is quite different on the output front. There we have digital outputs in the form of optical and coaxial toslink. Integrated DAC makes sure to provide us with two analog outputs: a pair of RCA connectors for single ended connection and a 4.4 mm Pentaconn for balanced outputs.

All major protocols are supported, including aptX, aptX HD, LDAC, AAC and so on. In the heart of analog section we have ESS Sabre Hyperstream DAC chipset.


I hooked Zen Blue to my main system, Cyrus 8vs2 + KEF LS50, and paired it with my smartphone. Pairing was quick and easy. Except different colors on the front of the unit, there’s even a voice telling you that device is paired and what Bluetooth protocol is being used – neat.

Then listening started. I was using local files of different qualities as well as Tidal stream. Zen Blue treated me with very listenable and enjoyable sound. Level of details is respectable and comparable to it’s wired cousin Zen DAC. Sound character differs a little bit though. Whereas Zen DAC offered warmer and almost fluid-like presentation, Zen Blue has a bit leaner approach. Blue’s bass notes sound less weighty but firmer, while midrange is somewhat sharper and more upfront. Vocals sound rich and present through both of the devices. In upper midrange and higher range Blue is favoring details over smoothness. I must say I prefer Zen DAC conically but the difference is not big by any means. On it’s own Zen Blue is quite capable DAC and you want feel lacking on the sound quality front, especially if you like its more upfront approach.


Next thing I was interested in is how good of a Bluetooth streamer Zen Blue really is. For that purpose Topping D50s came in really handy. First of all, it’s a very competent DAC. Secondly, it has an integrated Bluetooth receiver that sounds OK but nothing more.

I’ve connected Blue to D50s using optical cable and started listening. First thing that was immediately noticeable is that D50s has better analog stage than Blue itself can provide. Sound was simply more revealing, with weightier bass notes. Soundstage was deeper and populated with cleaner and better separated tones. I caught myself just browsing through my playlist, enjoying the music instead of taking notes, and that’s always a good sign. Quick switch to D50s internal BT receiver revealed that it is no match for Blue. Sound became mushier and softer. Bass notes were not as deep and punchy while other instruments didn’t have as clean edges and transients. At this moment I started to realize that some of the bad sonic traits I previously assigned to Bluetooth connection were much less obvious with Zen Blue.

This called for further testing and I connected Blue to the best DAC I had at hand – Burson Playmate. Sound coming from this combo was rich and meaty. Again, I found myself in a situation of taking a tour to enjoy the music instead of taking notes for the review. Switching between this setup and Playmate’s USB input finally showed the limits of a Bluetooth connection. As good as it was, music coming through USB had more micro details, leading edges had more byte and upper register was more airy. That said, I wouldn’t notice anything seriously missing in Blue-Playmate setup if I hadn’t made this direct comparison. That good and nicely balanced this wireless combo sound is.



Zen Blue is an interesting device. I think it’s made for those with specific demands. For those that put convenience in front of that last drop of sound fidelity accessible through wires. With its fine sound quality it makes a hell of a case for such a decision too. Its analog outputs are as good as you get in this price range. But by being able to sound this good over digital outputs, Zen Blue qualifies itself as an upgrade for any of you having a really good DAC already but wanting to enrich it with a Bluetooth connectivity.

. . .

You can find this and many other reviews on my website iwireviews.com

Video review:

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Pros: Great protocol support and output options, solid build, firmware upgradable.
Cons: May make you eat crow.

disclaimer: The Zen Blue was graciously sent to me by iFi Audio since I have been working on a stream of bluetooth devices. The Blue is one of several models in the Zen line and is a bluetooth streaming device. The other current Zen model is the Zen DAC and while similar in construction, it is strictly a desktop DAC/Amp and does not overlap the bluetooth functionality of the Blue. A big thanks of iFi-Audio. If you are interested in the Zen series or other iFi products, check their website.

Unboxing / Packaging:

The Zen blue ships in a lift top style box with the main unit housed in an egg-crate surround and the antenna, power cable, and RCA cables in a small box to the right of the unit. An instruction card and warranty card round out the package. If you are planning on using the RCA analog output, which is arguably the most common use case, you have everything needed to start using it immediately. If on the other hand, you want to use the digital output, you will need either a coaxial or an optical cable. The cable I most wish was included or at least offered via iFi’s website as an add on is the 4.4 balanced to dual XLR adapters for use with balanced gear. As of this writing, the iFi website does not list any such option. For those interested, I purchased a 4.4 balanced to dual XLR for testing from LQi Cables (I have no affiliation).


The Blue is a sturdy unit with a solid metal shell including the front and rear face-plates. Four screws run the entire depth of the unit and connect the front and rear faceplates. The board is slotted into the case so has no play in any direction when the screws are tightened down. The front face has a button on the left, a large central LED indicator with the iFi logo in the center, and an LED to the right that indicates connection status and pairing. The functions of the LEDs are discussed more in the connectivity session below. The rear face, from left to right, starts with the analog outputs. First the 4.4mm TRRS balanced line-out connector followed by the RCA connectors. The switch for analog or digital output rests between the RCA ports and the coaxial output port. A Toslink optical port is next in the sequence followed by the SMA antenna connector. At the far right, the 5V DC power input rounds out the back. The only thing that seems out of place in the package is the antenna as it does not look to be of the same quality as the main unit, nor does it match with the color scheme of the unit as it is bright white. One could argue that the antenna can be turned parallel with the unit but doing so either obstructs the power port and still sticks out 3 inches past the unit, or blocks all of the outputs except the 4.4 at the far left. I’m sure the antenna is a 3rd party made component and iFi was more concerned with function than aesthetic, but it does call attention to itself with its coloration (see below).


Ok, yes I cheated on the photos and they are iFi stock photos. It saves me taking apart the unit and potentially damaging a component. The main components of the Blue are the Qualcomm 5100 bluetooth chip, and the ESS Sabre DAC. IFi doesn’t mention specifically which chips are in use but the dac is one of the SOC type chips (ES9023, ES9219, or similar) that incorporate the 2Vrms amplifier with the dac chip. The board does not exhibit any identifiable op-amps in the signal path as would typically be seen if the chip were something like the 9018k2m. Likewise I suspect the Qualcomm chip is the QCC5124 as that is the only member of the family that does not support AptX adaptive and the datasheet for the Blue mentions AptX and AptX HD but makes no mention of adaptive. It is entirely possible that I am wrong on the exact model numbers as these are educated guesses based on iFi literature and what I can see in the stock photos.

The only input is Bluetooth with support for AAC, AptX, AptX HD, LDAC, HWA, and the standard SBC. Outputs include both digital and analog options with Coaxial and Optical digital outs and RCA and 4.4 Balanced analog outs. A couple of items worth noting at this point are:

The 4.4 balanced port is a fixed volume Line Out port and should not be used for headphones or earphones as the volume will be extremely high and potential damaging. The balanced port is designed instead for a 4.4 to dual XLR adapter for connection of the Blue to balanced inputs on another device.

There is a switch to the left of center on the rear panel that allows you to choose digital or analog output and only one or the other is active at any given time. Unlike some other models that will simultaneously send to both analog and digital, the Zen Blue is designed for either/or.


The Blue has both visual and auditory prompts for connecting a device so I recommend the following sequence for setting it up.

1.) Choose your output and make sure the selector is in the proper position

2.) Wire your output to your stereo or headphone amplifier and make sure the amplifier is on and you can hear output.

3.) Plug in the wall wart, and then plug the cable into the power port on the Blue itself.

If done in this sequence, you then have the benefit of having both the visual prompts on the front of the unit and the auditory prompts available to you as you pair your devices to the Blue.

At first the right most LED will blink blue. This is searching for previously paired devices. If none are found, the Blue will go into pairing mode and the LED will respond by blinking blue/red. The Blue can also be forced into pairing mode by holding the button down and waiting the LED indicator to flash blue/red before releasing it. The Blue can pair with up to 7 devices so can be switched between tablet and laptop etc without having to re-pair each time you wish to switch devices.

When a device connects to the Blue, the LED will become solid blue, and a visual and auditory prompt will tell the user what protocol is in use. Standard bluetooth connections (SBC) turn the middle LED (iFi Logo) green and are announced as SBC. Connecting an I-pad turns the logo yellow and announces as AAC. Connecting an AptX capable device turns the logo blue and announces APTX while AptX HD turns the indicator bright pink and announces APTXHD. Interestingly, LDAC and HWA are listed as supported by a future firmware update, but connecting my Sony and Motorola devices both announced as LDAC and turned the indicator a Cyan color. HWA should turn the indicator white, but I did not have an HWA enabled device to test with. Once connected and playback begins, the right most LED is used to indicate bit-rate. If the LED is blue during playback the bit-rate is 44 or 48 kHz. If the indicator is white, the source material is either 88 or 96kHz. I was able to do several tests with LDAC and high bit rate files and the Zen did identify all of them correctly. (As a side note anything over 96 is also down-sampled to that when sent via LDAC).

Distance from source to unit was good with nearly 25 meters possible in open space before reception started to drop. Single layer drywall didn’t defeat signal, but multiple layers easily did so source and receiver will likely need to be in the same room although it can be a fairly large room and direct line of sight between devices was not required.


Once paired and the music starts to play, the Blue does a good job of being a transparent conduit between source and amplifier. The typical ESS signature is on display with a slightly thinner, more detailed, and somewhat clinical output. I didn’t find this a problem at all as pairing it with a neutral to slightly warm system works very well and even when pairing it with a neutral system does not make it sound overly thin or sterile. Overall, detail level was quite good, and I was impressed with the quality of the sound when using LDAC and the higher bit rates.


There are lots of Bluetooth devices popping up to fill this space in the market, so where does the Zen Blue fit? I’ve had several of its competitors on my desk of late so here are some take aways from the compares

Xduoo XQ-50 – the least expensive of the bunch at around $59 retail, the XQ-50 is a well made little box, but lacks the style of the Zen and won’t compete in supported protocols either as it does not offer AptX HD, LDAC, or HWA. The XQ-50 can be used as a USB Dac which the Zen Blue cannot, but it is limited to 16/48 so is of limited utility. Also worth noting, the Zen offers balanced output which the Xduoo unit does not. This is a case of you get what you pay for. The Xduoo is a good value, but the Zen packs a lot more features in at only slightly more spend.

The Aventree Oasis Plus falls into the same class as the Xduoo with a retail of $70. Build of the Oasis+ is all plastic vs the Zen’s metal housing and the Oasis+ comes away looking like a toy next to the Zen. The Zen easily outclasses the Oasis+ as it is easier to pair, supports more and newer protocols, and has lower latency. The only point scored for the Oasis+ is that it can be used to transmit as well as receive. Overall, the Zen is simply a better option for those looking to add bluetooth input to an existing system.

Arguably the first two fall into a less expensive class of devices when compared to the Zen Blue. The next compare is on a much more even footing as the Auris BluMe HD retails at $120. The first thing one notices when comparing these two is the difference in size. The BluMe is roughly 1/3 the size of the Zen Blue. The down side is that the BluMe lacks coaxial and balanced output compared to the Zen and has its antenna on the front where it calls attention to itself. The BluMe also uses a micro-usb power input rather than a DC wall-wart. Both units support AptX HD, and AAC, but the BluMe stops there while the Zen Blue adds LDAC and HWA as well. I found both had roughly comparable antenna with no appreciable difference in distance between source and unit before break up became an issue. Unless you just love the diminutive size of the BluMe, the Zen Blue is the better unit.

And lastly, the AudioEngine B1 is the most expensive in this list at $189 retail. Both the B1 and the Blue are solidly built units with the B1 using a micro-USB power input rather than the DC wall wart style of the Blue. Size of the B1 is again considerably smaller than the Zen Blue and like the BluMe, the B1 has its antenna on the front in full view. The B1 has a single button on the front for power/pairing that also serves as the indicator light for pairing and power on. The B1 lacks the indicators for different bit rates that the Blue has, as well as the coaxial and balanced outputs of the Blue. The B1 supports AptX HD and AAC but again lacks the LDAC and HWA support of the Blue. Distance was again roughly comparable when the same protocol was in use.

Thoughts / Conclusion:

Well, I may be forced to admit that Bluetooth has a use case in audio. In its early days, I commented that I thought Bluetooth was an answer searching for a problem and I saw no real drawbacks to having wired headphones or sources that were large enough to accept the decrease in sound quality that came with wireless. Devices like the Zen Blue are forcing me to re-evaluate that position. It looks good, works as advertised and damn if it doesn’t sound good too. Having the ability to stream directly from my Ipad, or LDAC enabled DAP or phone directly to my home system with little loss of sound quality does provide an ease of use that none of the wired options rival. Sure streamers exist, but then you still have to have some form of wireless to control them remotely, and the ability to transfer from your in-ear to your home system and keep listening to the same song from where you left off is kinda nice. If the Zen Blue can make me rethink my position on the need for such a device, it has to have been easy to use, and work very well indeed. I’m sold. I think you will be too if you give it a try. The Zen Blue is a heck of a box for the price.
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