The iFi ZEN One Signature DAC sports the same 158x35x100mm aluminium enclosure as the rest of the ZEN range, finished in Deep Space Blue – the colour iFi uses to differentiate its Signature-level models – rather than the grey finish of the regular ZEN Series devices. This is complemented by dark grey front and rear panels (silver-coloured on the standard versions) and blue controls. The SPDIF Coaxial connection functions as either an input or an output. If the source is set to SPDIF, then this connector is automatically an input. If the source is set to either USB or Bluetooth, then this connector automatically becomes an output, allowing you to convert USB or BT to a digital connection to feed another DAC.

Of course, iFi custom wrote the firmware to run it in conjunction with their custom Burr-Brown DAC chips. This allows the ZEN One Signature to run in bit-perfect mode and also allows for direct hardware rendering. You have likely noticed that the ZEN One Signature DAC has a small white antenna protruding from its rear. This feature allows the product to receive a stable incoming Bluetooth signal and connect to your Bluetooth source. I mentioned Bluetooth there, because for my first few days with the Zen One Signature, I relied on it primarily as a reference against which to compare a number of standalone Bluetooth receivers for that aforementioned Wirecutter roundup. I also spent a good bit of time comparing its Bluetooth decoding to that of the Rotel A12MII.

The Zen One Signature is a DAC that comes in at just under 350€, placing it quite a bit above some of the recent devices I have reviewed from the brand, but still in the lower tiers of their price ranges (which range from under 100€ all the way up to over 2500€). The resolution and transparency were impressive. Every product we tried or tested from iFi Audio excelled in these two areas.

The new LAN iSilencer from iFi is supposed to clean and optimize the signal of an Ethernet cable via galvanic isolation when music is transmitted over it. Other devices in your audio set-up might come and go, but the ZEN One Signature DAC has been designed to be a future-proof “everything” DAC that can remain in your headphone or stereo set-up long into the future. It’s ready for any conceivable flavour of digital file, and its balanced topology makes it a viable contender for partnering with any number of high-end devices in your audio chain. Add stong Bluetooth performance to the equation along with compatibility with the latest hi-res codecs and you’ll be hard-pressed to want for much more out of your standalone DAC. As there is only minimal vertical modulation remaining at very low frequencies with an an actual cut LP that is playable, we know that “vertical modulation” at low frequencies must be warp. All of this is wrapped up in a sleek chassis that follows the curvilinear design common to all of iFi Audio’s Zen product lines. I think the thing I like most about the design, though, is its reliance on clear visual clues that tell you at a glance, from across the room, what it’s currently doing. The main iFi logo in the center, for example, glows different colors to let you know what format is currently being processed, dependent upon whether you’re relying on one of the physical inputs or connecting via Bluetooth. White means PCM or LHDC; cyan means DSD or LDAC; green means MQA or aptX Adaptive; blue means MQA Studio or bog-standard aptX; and magenta, as I understand it, means that the DAC is either acting as an MQA renderer after an external source has already done the first MQA unfold or, if you’re using Bluetooth, it means you’re getting aptX HD. And if the light is off, that means you’re listening via Bluetooth but with standard SBC instead of any advanced codecs.

Balanced. Blissfully quiet.

We used the DAC wirelessly to test its connectivity. To our surprise, its long-range performance was excellent when keeping the transmission in a straight visible line. The Atom lives on my desk (fed from a Modi 3+) and is basically my permanent feed for the KPH40, which I use for conference calls, simple media consumption etc. throughout the day. Rather than be patient, I took the Atom and plugged the unbalanced feed from the Z1S to it and proceeded to enjoy the rest of the day. I actually enjoyed the combination so much that, although I brought another couple of amplifiers into the office, it was a few days before I finally got around to swapping out the amp. I compared the Signatures’ BT output to the output of the 6000A Play’s internal BT receiver, and I found the iFi connection to be superior in every way, providing a more nuanced and transparent presentation. Purity of design, no headphone amp, no volume control. The ultimate DAC for all your home audio sources. HD Bluetooth It is also worth noting that, while the Z1S will work with just a USB connection, when powered by the included power supply, there is a noticeable increase in volume. This increase in volume actually also seems to increase the clarity and separation, yet this is probably just the mind interpreting it that way due to the volume increase. Perceived or real, I have to say that I prefer it with the iPower II in use.

The ZEN One Signature’s ‘digital engine’ is based around a Burr-Brown DAC chipset that iFi uses extensively, selected for its natural-sounding ‘musicality’ and True Native architecture. iFi’s experience with this IC means it knows how to make the most of it; but whilst intrinsic to the resulting sound, the creation of an exemplary DAC stage involves much more than the selection of a particular DAC chip. There are two LED windows on the front panel which first off and foremost indicate power-on status. The multicolor LED window on the right indicates the format of the digital input or the Bluetooth codec level. The Zen One Signature DAC is an excellent home audio device. It delivers colourless and flat yet detail-oriented audio while retaining energy and dynamics. Plus, it offers good resolution and separation, allowing you to enhance its neutral sound with other gear. The ZEN One Signature’s singular purpose is to take the digital audio signal from any device, via cable or Bluetooth, and convert it to analogue to feed an external amp and speakers (or headphones). Coupling high-quality internal components with iFi’s class-leading circuit design, it delivers a brilliant boost to sound quality however your devices connect to it. For many, the ZEN One Signature is the one and only DAC they will ever need in their home. iFi Audio is an award-winning audio tech company dedicated to enhancing your music enjoyment. With a mission to improve sound quality and eliminate noise, distortion, and hiss, iFi Audio offers a wide range of products that cater to headphones, speakers, portable audio devices, phones, and TVs. By doing so, they aim to deliver studio-quality audio that allows you to experience music as the artists intended.Is the design of this product good, or is it nothing to bother? How about its functions? Are these efficient enough to get the job done?

Adding a ZEN One Signature DAC sounds like a promising way to make any audio set-up a whole lot “smarter” when it comes to adding digital audio upstream - let’s see what it’s like to live with, and how it sounds. ZEN One Signature DAC - what is it? One last thing to note is that the output of the Z1S, from the unbalanced RCA’s, is over 3V, which is quite a bit more than the usual approx 2V output of an unbalanced connection. This can actually cause clipping on the input of certain amplifiers, depending on the design of their preamp stage. As there is no volume control on the Z1S, you would need to drop down the source to avoid this if it is your case. The rest of the circuitry seems iFi Audio solid as always. They customarily employ some well-known components for circuitry control and power delivery and always display a “spare no expense” attitude. The iFi Audio ZEN One Signature is not the exception. The ZEN One Signature is a pure DAC (no built-in headphone amp and volume control) that serves as a home audio hub for all your digital devices, from smartphones and tablets to PCs and Macs, disc players and audio servers to TVs and games consoles.One small issue with all original Zen DACs was that when they switched formats from MQA to FLAC or DSD, they emitted a low-level “pfft” noise. From user-group complaints, I have to assume that iFi is aware of this issue and may have a solution, though it has not made any changes in the Signature to eliminate this behavior. The Zen DAC Signature still makes the same soft “pfft” noise after every format change, just before the music begins. Will iFi come up with a firmware fix? Time will tell. Making full use of Qualcomm’s latest four-core QCC5100 Bluetooth processing chip, every current high definition Bluetooth audio format is supported, including aptX Adaptive and aptX HD, LDAC and HWA/LHDC. Other codecs covered include regular aptX and aptX Low Latency, AAC and SBC (the ‘plain vanilla’ Bluetooth codec). MQA (the format used by Tidal for the Masters files found in its HiFi Plus tier) is also supported, with full decoding up to 384kHz, meaning that the complete ‘three unfold’ decoding process is performed internally, as opposed to just the final unfold in the manner of an MQA ‘renderer’. We also appreciate the company for giving the product a 12-month warranty for convenience. Hands-on with the ifi Zen One Signature DAC