iFi Audio ZEN Stream Review
- Tremendously flexible specification
- Well made
- Keenly priced
- Some minor stability and set up niggles
- Slightly ungainly front panel
- Not yet as stable as an SOtM
Introduction - What Is the iFi Audio Zen Stream?
The iFi Audio Zen Stream is a network streaming transport. This is an exciting collection of words that needs a little in the way of explanation to fully cover what it can do (and we’ll do that, don’t worry). Unlike the Mk2 versions of the Zen products that we have been looking at of late, the Stream is all new and has no predecessor either in the Zen range or anywhere else in the iFi line up.
This is because the Stream is part of a category of product that is still in the early stages of its existence and might yet not become truly mainstream (it wouldn’t be the first time that a really good idea hasn’t quite captured the public’s imagination). Instead of being a self-contained streamer, the Stream contains the network audio hardware but outputs a digital signal to be decoded elsewhere. With the proliferation of digital inputs on everything, this would seem like a very logical way of going about things but - it comes with additional complexities too.
The Stream is a very bold attempt to simplify some of those complexities and - as is the way that iFi goes about doing things - to deliver it at a ‘category killer’ price tag. Given that it is a first attempt at the same time, this is a fairly ambitious thing to be doing. Can the Stream deliver on the considerable promise it offers and bring streaming transports to a wider audience? Let’s plug it in and find out.
Specification and Design
Before we get stuck into the nuts and bolts of the Zen Stream, it’s worth noting that although this is a rather specialist category, we do have some points of comparison on the site already. In 2019, I reviewed the SOtM SMS200 Neo; a device that so perfectly met my needs for test work that I bought it before I even started writing the review for it. Not that long after, as part of the testing for the sublime Lindemann Limetree Network, I also covered its sibling, the Limetree Bridge which offered a slightly different take on the concept (in that it is designed to bring modern streaming functionality to the inputs of older DACs). Additionally, companies like Auralic, Lumin and Chord Electronics also have their takes on the concept too.
The Stream has some things in common with the SOtM and Lindemann but in some critical areas it differs again. The main area of difference is that iFi has been extremely ambitious with the number of ways that the Zen Stream can be used. To begin with, in the most straightforward method, it can be controlled via dedicated UPnP app. You can then also control it via third party UPnP apps such as Kinsky, Bubble, MConnect et al. The vast majority of Streams will likely find themselves being used in this fashion.
iFi is only getting started though. The Stream also supports Tidal Connect and Spotify Connect so if these are your primary sources, it has you covered there too. It functions as a Roon Endpoint too which is potentially very handy. Then, it also has the specialist Network Audio Adapter software that is designed to function with the HQ player software. Then, in order to complete an impressively comprehensive spec, the Stream also works over AirPlay (with AirPlay 2 and Chromecast being promised) too.
Neither is iFi done there. Its hope is that the Zen Stream has enough stretch to support some other network applications too. The obvious candidates would be Minim, Logitech Media Server and Volumio and it’ll be interesting to see what can be achieved in this direction. Obviously, the standard mantra of AVForums reviews that you should only buy a product for the features it has rather than the ones that are promised applies as much here as it does for TVs but the Stream does a fair amount already.
The hardware that iFi uses to achieve this is impressive. It’s built around an ARM Cortex processor that is integrated into a circuit that makes use of the various performance tweaks that iFi considers imperative to what it does. This means that the circuit includes some relatively high spec components such as TDK C0G capacitors and Murata Inductors. An example of the GMT (Global Master Timing) clock circuits is present too. iFi takes an approach that, in fitting these devices to as many products as possible, it can better leverage the costs.
A decent wall wart PSU is supplied which works with high quality regulators and a 1.5MHz high speed supply controller to keep things as stable and quiet as possible. The Stream uses the metal casework as a heatsink and has no fans, vents or other convection system which means it is completely silent in use. It does run warm though - warmer than either the SOtM or the Lindemann.
This circuitry operates over wired and wireless internet, with an external aerial to boost wireless reception and 802.11a/b/g/n/ac support. It makes its signal available to a pair of USB outputs and a single coaxial digital output. This latter connection is significant because it means that the iFi bridges the gap between the USB only SOtM and optical and coaxial only Lindemann. Sample rates up to 384kHz and DSD256 (as well as full MQA unpack) can be received and passed to the USB out with the S/PDIF making do with 192kHz and DSD64.
This is a lot of capability for the money but it’s only fair to point out that there are - at the time of writing at least - some costs associated with getting this much done. First up, as a matter of course, the software was updated to the latest version. Habit as a reviewer is to simply connect the device to the router and get it to check for a newer version. Oddly, in this setting at least, the Zen Stream didn’t want to do this. It only seems to possible to get the app (and with it, access to software) up and running as part of the wireless set up. Putting the Stream on wireless is well explained in the documentation but the process did not work for me at all on iOS but did on Android. Once this is done, the app will connect over both wired and wireless. Author's note October 2021. A second test of setup after a more recent firmware update did not exhibit this issue suggesting it has been successfully resolved.
With this done, the control experience of the Stream is good - particularly for a brand new app - but it faces stiff competition. The problem for the Zen Stream is that the SOtM that lives here might have to rank as the most unconditionally stable network device of any description I’ve ever tested. After over two years of ownership, the downtime experienced by the SOtM stands at 0 (zero) minutes. The iFi has needed a reset in the time it has been here and the sample rate indicator stopped lighting up at one point, also requiring a restart.
Now, it is only fair to point out that the SOtM achieves some of this stability by being drastically simpler than the iFi. Each mode of the SOtM must be selected and locked in so if (as I do) you use it as a Roon Endpoint, it can’t be accessed in any other way. The iFi by contrast can have different operation modes locked in via a rotary control on the rear panel but has an ‘anything goes’ setting that means you can use it in various different ways at once. The SOtM also has no wireless and no control app of its own. The Lindemann has both of these things (and can move between Roon and UPnP freely) but it’s nearly twice the price of the iFi.
Call it intuition but at this point a subset of people reading this will point at a homebrew solution involving a Raspberry Pi and decry the extra cost of the Zen Stream. This is valid up to a point. Leaving aside arguments over the relative quality of network hardware, the argument is simply one of time, convenience and capability. If you’re a dab hand at this sort of thing, the Pi might well make more sense but, if you aren’t, be sure to calculate your hourly rate and work out how much the set up time will cost you before you work on the principle that the homebrew option is automatically cheaper. In an entirely subjective area, I’d also point out that very few of the Pi based devices I’ve seen are finished to the standard that the Stream is. This might not matter for all people but it does need to be taken into account when making comparisons.
The Stream uses the same casework as the other Zen devices which means that it is a solid little device, even at the rather higher price than the other Zen components. Aesthetically, It’s not the strongest member of the family. I don’t like the large ‘STREAM’ logo on the front panel (if you’ve paid your own money for one, I’m guessing you know what it is) and the larger LED indicators that show network status and sample rate aren’t terribly elegant. The iFi conspires to show no more operating information than the Lindemann in a larger and less elegant way. It is well made though and there’s an equally valid user case for simply parking it out of sight, in which case who cares what it looks like?
The use cases for the Stream are interesting. iFi (obviously) considers the recently updated Zen DAC to be the prime candidate and some testing did take place with that but I’m not sure it’s the perfect match. The cost weighting of £400 on interface and £159 on decoding doesn’t feel completely natural to me and I suspect that many Streams will find themselves working with rather more expensive non iFi decoding. The argument for this is - to me at least - fairly compelling. Take something like the Cambridge Audio Edge A; the device that I’ve done the most testing of the Stream with. On its own the Edge has digital inputs, HDMI ARC and Bluetooth as well as analogue line ins. Add the Stream to the USB input and it’s a complete hardware package and the same applies to any amp with a USB (or even an S/PDIF) input and, as the price of the amp climbs, so the £400 asking price becomes more discretionary.
The Stream has some things in common with the SOtM and Lindemann but in some critical areas it differs again
How Was the Zen Stream Tested?
The iFi has been run in wired and wireless conditions connected to an iFi Zen DAC v2, a Cambridge Audio Edge A, a Cyrus i7 XR and a Chord Electronics Hugo Mscaler and TT2 DAC combination in place of the standard SOtM SMS 200 Neo. It has been used in Roon mode, UPnP and Tidal Connect and an iPad Pro has been used for control and AirPlay testing. Material used has been FLAC, AIFF, DSD, Tidal, Qobuz, Spotify and some limited internet radio.
More: Audio Formats
As you might imagine, this section is rather shorter than the front end of this review because the iFi is just that; a front end. This means that the performance of the partnership will be decided in the main by the decoding of the equipment you have connected to the Stream. This in turn means that connecting the Zen DAC MkII gives you a pairing that - even judged at the £560 combined price point is a seriously flexible and talented partnership - and one that only needs a single mains plug to work as the Stream can power the Zen DAC.
I stand by my comments that it’s amplifiers with decoding on board that are the true happy hunting ground for the Stream though. Listening to the Cyrus i7 XR connected to the Roon Nucleus via USB and then moving it and the Stream upstairs and running them there, gives exactly the same performance. This might sound anticlimactic but it means that the Cyrus is transformed into a self-contained system that works anywhere. No less importantly it works reliably too. The Stream routinely rejoins the wireless network when you power it up and the connected USB device is consistently rediscovered. The Edge A has been a partial exception to this but that is also the case with the SOtM, so I am content to point the finger at that rather than the iFi.
No less importantly, the other functionality the Stream has over the other devices of this nature I have tested, like Tidal Connect and AirPlay, broaden the appeal further. I’ve not perceived any benefit to locking the Stream in a single ‘mode’ so being able to AirPlay YouTube content to it when Roon draws a blank has been something I’ve really appreciated.
I stand by my comments that it’s amplifiers with decoding on board that are the true happy hunting ground for the Stream though
iFi Audio ZEN Stream Review
At the time of writing (late August), the Stream has not been on sale for very long. In a category where one notional rival has achieved broadly unconditional stability, the Stream probably can’t match the same claim. There are two things to consider though. The first is that the Stream makes the SOtM look decidedly limited in terms of functionality. This is a device that has some really impressive bells and whistles to hand - and there’s the promise of more to come. The second is that as the Stream’s software develops further, I can see it achieving the sort of bulletproof behaviour of the more established rivals. Whether you need a device like this will come down in part to the solutions you already have to hand but, if you are eyeing up an amp with digital inputs, this is the device that turns it into a complete system. The Stream is ambitious, capable and flexible. It’s not perfect (yet) but it’s seriously impressive nonetheless and comes Highly Recommended as a result.
Our Review Ethos
To comment on what you've read here, click the Discussion tab and post a reply.