Stack Audio Auva 70 & Auva EQ Review

Even when we reach a point where we're happy with something, there is still the urge to improve it – whether that means finally sorting out the loft insulation, tuning your car, or tweaking your hi-fi system. While there are plenty of hi-fi accessories out there, few brands offer a 30-day money-back guarantee like Stack Audio.

From the comprehensive range of isolation products offered by the British company, we have the mid-level Auva (AUdio Vibration Absorber) 70 loudspeaker feet and EQ equipment isolator on test here. The former is machined from a solid aluminium billet and has three cells packed with a carefully selected blend of particles, including tungsten powder. I'm told that the vibration forces particles to collide and that the vibration dissipates via heat. There is much more to it than that, but Stack is understandably cagy about disclosing too many details.

Each Auva 70 speaker foot (£840 for eight) measures 70mm in diameter and 30mm high, excluding the top bolt or spikes. In addition to a variety of thread sizes (M8 threaded bolts and adapters), you can also choose 15mm or 25mm spikes, or rely on the pre-fitted felt pads to best suit your flooring. This means they are compatible with a wide range of loudspeakers up to 275kg per side, so comfortably accommodate my 40kg per side Audiovector R6 Arrete.

Meanwhile, the Auva EQ equipment isolator (£198 for four) uses what Stack calls a 'custom silicone absorber' (CSA to its friends) at the base of each EQ, alongside particle-impact damping. The CSA secures the EQ to the equipment shelf, forming a level of decoupling. The CSA insert is height-adjustable and available in three versions to best suit the weight of the equipment it will be supporting.

Stack Audio recommends placing the equipment's chassis directly on the EQs, rather than balancing the component's supports atop the EQs. This was perfect news for me as I wondered how I'd balance my MOON DAC's pointed feet on them. For this review, I was sent sets of CSA 1, compatible with equipment weighing 1 to 16 kg (using 4), such as my 10kg Oppo UDP-205, and CSA 2, suitable for 16 to 40 kg (using 4), which would support my 18kg MOON 681D DAC, for instance.

Everything, from the packaging and the included tools to the overall fit and finish of the isolators, is top-notch and what one would expect from a high-end product.

The Listening

I immediately noticed better instrumental definition and less bass smear, with the Auva equipment isolators in place. This resulted in superior midrange clarity, benefiting vocals, percussion, and even bass guitar. As my hi-fi components already sit on Solidsteel shelves, I wasn't expecting a huge difference, but there was definitely a subtle yet noticeable improvement.

This was even more evident when I removed them and returned to what I was used to, which suddenly sounded flatter and more opaque. Moving back to the Auras in situ, and the low-frequency interaction between the kick drum and bass guitar sounded more together.

With the Auva speaker isolators in place, I noticed tracks such as the dreamy Space Song by Beach House enjoyed better separation. Even the classic My Bloody Valentine track Only Shallow became slightly more focused, which is quite an achievement. This additional focus also had a knock-on effect, with the higher frequencies making the hi-hats sound more energetic in tracks such as Rush's nineteen-seventies prog classic Subdivisions.

Together, the Auvas made a subtle but clearly audible overall improvement to my reference system. Bass was tauter, midband detail cleaner, and there was a better sense of space and depth perspective with improved imaging precision. Although these accessories will improve most systems, you'll get the biggest improvement if your system is already highly revealing.

The Verdict

If you own a proper, purpose-designed hi-fi rack, then most of the heavy lifting should already be done for you, in terms of vibration control. Likewise, good loudspeakers should have proper spike systems already fitted. All the same, these Auva products from Stack Audio really do help out in some situations. Beautifully made, elegant-looking, and – most importantly – sonically effective, they can clear up your system's sound. And with a 30-day no-quibble return policy, you can experiment at your leisure. Recommended, then.