Review: SparkoS Labs Aries Headphone Amplifier

SparkoS Labs Aries

Sound impressions and pairing:

Andrew explained that SparkoS Labs were aiming for “a straight wire with gain” with the Aries, in order to achieve “…transparency and clean sound that was faithful to the original source material as possible”. I can say without certainty that they’ve managed to deliver upon this objective – the Aries is powerful, vivid, and controlled. There’s absolute silence between the notes on the Aries – even with sensitive headphones and IEMs – and that helps to contribute to what amounts to an utterly faithful and lifelike presentation of your source material. The Aries has seemingly endless reserves of power, and its tremendous dynamic capability means it is able to recreate the contrast and drama in your favourite recordings, presenting genuine ‘light and shade’ rather than simply blaring it back. 

Power-wise, SparkoS Labs explained that the Aries can drive “about 14V and supply about 350mA” and it has “…a couple of watts at 32 ohms, and about a half a watt at 300 ohms”. What that translates to (roughly) is just about ‘future-proof’ power to drive just about any headphone on the planet. I spent the best part of a month listening to the Aries with a range of low/high-impedance dynamic headphones, low-impedance planars, and even IEMs. And the Aries proved to be as versatile as it is powerful. 

Headphone pairing

I spent a lot of time listening to the Aries with the Sennheiser HD650. More than any other headphone, the HD650 can be very source-dependent and revealing of source gear. The HD650 was a joy to listen to with the Aries, which is capable of waking-up the very capable and full bass reproduction that lives inside them (when fed with appropriate power) while removing the slight hint of rolled-off detail that can result from some amps. The ‘-35dB’ mark on lowest gain setting (around ⅓ of the dial) is enough to get the 300-ohm Sennheisers singing. Listening to ‘Jambi’ from Tool’s ‘10,000 Days’ album, the Aries shows itself to have a slight edge in dynamics and an overall more energetic presentation over the iFi Pro iDSD on the HD650, with Danny Carey’s drums hammering-away with incredible impact and realism. 

SparkoS Labs Aries

SparkoS Labs Aries

One of the advantages of the Aries is its ability to work with absolute finesse when playing with sensitive headphones thanks to that volume-pot. The Grado PS500e is both incredibly sensitive, as well as transparent to a fault – it can usually run into troubles with channel imbalance with powerful amplifiers, as well as venture into ‘fatiguing’ territory with unrefined sources. The Aries paired with the Grados serves-up elegant 3D layers of vocal reverb and delicate synth in The War of Drugs’ ‘Disappearing’, with terrific attack and decay.

While the open-back variety of the Aeon Flow from Dan Clark Audio (formerly ‘MrSpeakers’) is only 13-ohm impedance, they are fairly insensitive and really do require a hefty dose of power to perform at their best. The Aries more than ‘wakes-up’ the diminutive planars, it unleashes their full dynamic capabilities – and when coupled with their rather nice tonal balance, it makes for a great match the Aries. Steely Dan’s ‘Josie’ bounces along with taut, articulate bass, lightning-fast percussion, and snappy brass.  

Sparkos Labs Aries

SparkoS Labs Aries

I’m an absolute sucker for the organic tone of the Eikon from ZMF, and the Aries captures the innate potential inside their bio-cellulose drivers and delivers it back in spades. If you’re not a fan of Frank Zappa…well you should be – listening to ‘Nanook Rubs It’ from his 1974 album ‘Apostrophe’ was perhaps my most enlightened moment during my time with the Aries. The way the Aries unleashed the sub-bass, imaging skills and natural dynamics of the Eikon during the multiple vocal tracks at 2:45, and the entry of the horn-section at 3:06 is just about as good as it gets. Wow. 

I tested the Aries with the new Audio Technica flagship IEM, the ATH-IEX1 (stay tuned for the review, coming soon!) to see how it was able to match with sensitive IEMs. The ATH-IEX1 only needed the very lowest few notches of volume to reach full-volume on the Aries, -51dB was plenty to get AC/DC’s ‘Whole Lotta Rosie’ absolutely rocking – and of course, with absolute accuracy between channels. A quick play with the volume-pot (with music firmly switched ‘off’) showed that there was no audible ‘hiss’ whatsoever until -15dB on the volume pot. This is one seriously quiet amp. 

Source pairing

Source-wise, I did prefer the Aries with a slightly ‘sweeter’ or warmer upstream pairing. The Chord Mojo was a terrific sonic match with the Aries as opposed to the more clinical delivery of the iFi Pro iDSD, but switching the iFi’s tube-mode made for a sonically-blissful match that sounded genuinely analogue. Speaking of analogue – I put those RCA inputs to good use, pairing the Aries with my turntable for some hugely enjoyable playback. It’s an incredibly revealing amp, so don’t expect it to hide surface noise as well as all the ‘snap crackle and pops’ if your record is dirty or damaged. The more laid-back presentation of the HD650 made for a good match in this regard, and I thoroughly enjoyed spinning literally dozens of LP using this set-up. 

SparkoS Labs Aries

SparkoS Labs Aries


It’s incredible to believe that the Aries is the first end-to-end product from SparkoS Labs, as it is simply so cohesive in terms of how well it’s packaged combined with how it performs. Its build is bullet-proof, the user-experience is first-rate, and sonically it’s immaculately transparent yet utterly enjoyable. What SparkoS Labs has by way of advantage versus the competition is access to an incredible ‘parts-bin’, but the Aries is just so much more than the sum of its parts. The Aries is at once utilitarian and powerful, while also managing to be refined and finessed – and it’s simply a joy to have on your desktop.

For a $2,495 opening price, the Aries is certainly up against some stiff competition. For context, the Schiit Ragnarok that we reviewed recently also packs a speaker amp, and balanced topology – for a grand less. At this price, I’d prefer a headphone amp to have balanced connectivity for convenience more than anything, seeing as many TOTL headphones are likely to be terminated in 4-pin XLR, but seeing as there’s no audible difference it’s not a deal-breaker.

So why should you consider the Aries? There’s a lot to be said for products not being designed by committees, and thankfully the Aries is not. Having spent some time with the Aries, you get the distinct impression that SparkoS Labs wanted to deliver upon a singular vision of perfection – utterly uncompromised performance (and certifiably measurable) in its purest form. And anyone looking to find a no-compromise headphone amplifier as a part of their system for years to come should absolutely have the Aries on their consideration list – SparkoS Labs offers 30-day returns in addition to a 5-year warranty.

The Aries has been a joy to listen to, and its performance and build certainly live up to its pedigree and price-tag. It’s genuinely impressive.  


Matty's a musician, music-fan, and 'gear-phile' from Sydney, Australia. Outside of his day-job in creative advertising, Matty enjoys live music, lawn bowls, craft beer, and spending far too much money collecting vinyl.

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