Cyrus SoundKey


Tech Specs

  • Type: DAC & Headphone Amp
  • Casing: Robust Aluminium
  • Formats: MP3, AAC, FLAC etc
  • Resolutions: up to 24bit/96kHz
  • Power Consumption: 50mA
  • Weight: 16g estimated


Cyrus SoundKey DAC and Headphone Amplifier is designed to feel like part of your headphone cable. Plug between your phone and headphones for greater listening.

If one were to draw up a list of possible contenders for hi-fi ubiquity a year or two ago, safe to say that, only the prescient few would have put ‘portable DAC’ anywhere near the top.

And yet here we are. The prevalence of digital music, and the enormous storage capacity of some portable music players and smartphones (not to mention desktop computers), means we can access all our favourite music no matter where we are.

But what’s the point if it sounds unsatisfactory?

The majority of DACs and headphone amplifiers fitted to smartphones or laptops are the cheapest and most plentiful the manufacturer could find. And we all know what the results of that kind of policy are – just listen to the way your laptop neuters your favourite tunes when you plug your headphones into its socket.

Designed For Your Phone

Phones are not designed as audio playback devices, so the cheap interior means music lovers aren’t getting the sound quality they deserve. To resolve this, Cyrus poured their extensive audio expertise into creating the Cyrus SoundKey; a new high-quality DAC and amp.

Cyrus SoundKey – Sound

The first thing that strikes us about the soundKey is the remarkable amount of space it gives to the presentation of a song.

This is especially pronounced when listening to quieter, sparser material – a 320kbps Spotify-derived file of Lotte Kestner’s Secret Longitude is a particularly good showcase of the Cyrus’ powers of separation.

It opens the recording wide, allowing the tiny details space to reveal themselves and giving the tune a widescreen aspect some lesser portable DACs are simply not capable of.

This winning quality is even more obvious when we up the ante to a 24-bit/96kHz file of Aretha Franklin’s I Never Loved a Man (the Way I Love You).

It’s a slow-burner of a tune, intense but not all that demonstrative where dynamics are concerned – and the Cyrus establishes a big, well described stage for the players to inhabit.

At the same time, it reveals all the character and technique of Aretha’s inimitable vocal in the most natural way.

Shifting gears more than somewhat with a 16-bit/44.1kHz stream of Melt-Banana’s Candy Gun via Tidal reveals the soundKey to be reasonably, thought not decisively, dynamic – it has all the fevered abandon the tune requires, but doesn’t quite describe the peaks and troughs as explicitly as some rivals.

Comparison with our current favourite at around this price, AudioQuest’s DragonFly Black, highlights the soundKey’s relative shortage of out-and-out dynamic heft – but at the same time, the Cyrus achieves the remarkable feat of making the Black sound like something of a blunt instrument. It’s significantly more revealing, more open and more detailed than the AudioQuest.

If we’re asked to make a trade-off between transparency and ultimate dynamism, we’ll come down on the side of the Cyrus every time.

Built on Audio Expertise

For over 30 years, Cyrus has won multiple international awards for their products primarily attributed to two core skills in amplifier and DAC design. The key to this is in the power supply. Cyrus understands amplifiers do not actually amplify, but instead make larger copies of the original source signal. Therefore, the quality of power used to make the copy is critical to the ultimate quality.

When a product needs to be as compact and unobtrusive as possible, there’s little scope for building in perceived value. And it’s true that, despite the smoothly seamless build of the soundKey, it doesn’t necessarily look like $160-worth of hi-fi kit.

It weighs in at 18g and is just 8mm deep – excellent from the portability point of view. The aluminium casing feels good, and is nicely chamfered. The logos (‘Cyrus’ on one side, ‘soundKey’ on the other) are raised just slightly to give both tactility and grip.

There’s a choice of four finishes (red, purple, black or turquoise) and, in fairness, it’s difficult to know what else Cyrus could have done with a product designed to be as discreet as possible to make it seem any more upmarket than it does.

High-Quality Components

Plug Cyrus SoundKey into your phone, tablet or laptop for unbeatable sound on the go. The high-quality components deliver music with a greater sense of space so you hear individual instruments, voices and melodies more clearly.

Detail is greater making subtle nuances in vocal intonation more apparent. There is a better grip on the lower frequencies allowing bass notes to sound more tuneful driving their own rhythm without being just ‘heavy and loud’. Overall, the performance is more emotionally engaging and enjoyable.

Compact and Lightweight

One of the main things setting the Cyrus SoundKey apart from rivals is its extremely compact size and design. Since listeners using their phone as a music source are likely to be on the move, being small and lightweight is essential. It weighs only 16 grammes (est). From a design perspective, smooth rounded edges enable it to feel more like an integral part of the cable without catching or snagging on anything.


We had a good listen using various headphones and wired earphones, and a variety of platforms. We used the Pixel 2 mentioned — we had to use a generic USB Type-C to Micro-B USB cable for this — and a Samsung Galaxy S7, and a Samsung Galaxy Tab A tablet. All worked perfectly well, recognising the DAC and routing their audio to it.
Likewise our iPad Mini 4, our Windows 10 computer, and our Mac Mini. Having checked that everything worked, we did most of our listening and testing with Android phones and the Windows 10 computer.

Clearly Cyrus’ high fidelity heritage has been brought to bear. As we’ll see shortly, just about all the tech stuff ticks the relevant boxes, but we were impressed just as much with the sound. There was excellent control of all our headphones. We mostly used three sets of head-gear. First, there was our old Sennheiser HD535 headphones — they have an open design and are quite insensitive and have a fairly high 150-ohm impedance, which can make things difficult for portable gear. Then there was our Oppo PM-3 headphones — which are quite sensitive, closed-back and which offer only 26 ohms impedance. That impedance is even across the full range of audio frequencies. Finally, there were our Sennheiser Momentum Free earbuds, which are rather high quality as these things go, and even lower impedance at 18 ohms.

All our music sounded excellent. Had we not known what device was being employed, we’d have been hard put to say that it wasn’t a high-end DAC and headphone amplifier. Even with fairly complex music playing at quite a high level, the Cyrus soundkey remained smooth, yet powerful.

Just as importantly, it tended to impart as slight sense of distance to the music, so there was less of the ‘in our head’ experience, and more of an ‘out there’ experience.
Noise? It was completely inaudible to us, regardless of platform, and that includes the Windows computer plugged into power. And even with the old high-impedance low-sensitivity Sennheiser headphones, there was ample volume available. Which is impressive, given that the system is relying on the 5V USB power supply. (We note that Cyrus says that the device is suitable for headphones only between 16 and 64 ohms, lest others not be loud enough. That proved not to be a problem for our listening.)

There was really only one problem: the higher sensitivity devices had to operate with the volume control right down near the bottom of the range when we used it with Android devices with our preferred USB Audio Player Pro app. That made it hard to adjust the level precisely. But perhaps it was the player as much as anything. This one is optimised for use with external DACs, but for some reason the ‘hardware volume control’ slider within the app wouldn’t work. With Spotify there was no such problem. A good listening level was in the middle of the phone’s volume range.

We ran some measurements, confirming noise to be impressively low. With 24-bit/96kHz signals it delivered -103.5dB (A-weighted) noise levels. Repeating the test using a computer running on power and running from battery, the power produced a little breakthrough at 50Hz and its harmonics, but that remained inaudible. Most of the noise floor was below -130dB and the 50Hz peak was at -110dB. The noise levels with 16-bit audio were at -96.8dB, A-weighted.

With 96kHz sampling, the high-end response was extended, down by 1dB at 36kHz and 1.5dB at 44kHz. Bass rolled off too, which was unusual, down by 1dB at just under 30Hz and 1.5dB at 20Hz. With 44.1kHz sampling the top end was maintained all the way to 20kHz, down perhaps 0.1dB, above which the output hit a brick wall.

Low Current Device

Cyrus SoundKey is an extremely low current device that deliberately does not use a separate battery. This keeps it small and light and means you don’t have another thing to charge. Powering it relies on your phone battery however while other DACs typically drain 100mA, the SoundKey has been designed to draw only 50mA efficiently conserving battery life.

Key Features

– Awesome sound quality
– Small and lightweight (around 16g)
– Smooth sleek design and robust aluminium casing
– Extremely low current, conserving your phone’s battery life
– Compatible with many audio formats including MP3, AAC and FLAC
– Can handle high-resolution audio files up to 24bit/96kHz