STACK AUDIO AUVA EQ EQUIPMENT ISOLATORS REVIEW

John Scott spends some time with Stack Audio’s AUVA EQ isolators (£198 for four).  

I like to think of myself as a “real world” HiFi reviewer.  I have two HiFi systems in my home in rooms that are used as communal living spaces by my family rather than as dedicated listening rooms.  While I strive for my HiFi systems to sound their best, this needs to be done in a way that minimises the physical or aesthetic impact on these spaces so acoustic treatments like bass traps or absorption/diffraction panels are not an option. 

Last year I had the opportunity to review the AUVA loudspeaker isolation pucks from Stack Audio.  These fitted discreetly below my speakers and made a hugely positive difference when tried in each system; a win-win as far as I was concerned.   As anyone with an interest in HiFi will be aware, a degree of scepticism exists when it comes to the audible benefits arising from HiFi accessories; following my review of the AUVAs, I read several comments about “confirmation bias” (basically only hearing an improvement because I expected to do so rather than any real improvement having occurred). All I can say is that the AUVAs remain an integral part of my main system a year later and won’t be going anywhere anytime soon so when the opportunity arose to give Stack Audio’s AUVA EQ equipment isolators a try, I was keen to see if they would be as effective as the speaker isolators.

 

Before we move on to the EQs, it may be helpful just to recap a little on the AUVA speaker isolators and how they work as the equipment isolators follow the same philosophy.  The AUVA speaker isolators were designed to firstly provide the speakers with a firm footing by coupling them firmly to the floor and secondly isolate the speakers from vibrations by absorption. This was achieved primarily by the use of a patent-pending technology involving particles of material, including tungsten, to effectively kill vibration in its tracks and convert it to heat, both removing vibration from the speaker cabinets and protecting the speakers from external vibration transmitted through the floor. As mentioned above, the EQ equipment isolators use a similar, if slightly simplified, approach. 

UNBOXING AND BUILD QUALITY

In my review of the AUVA speaker isolators I remarked upon the quality of the packaging and, unsurprisingly, the EQs are presented within a similar box which once again adds to the feeling that this is a quality product and not just an off-the-shelf accessory.  Foam inserts within the box ensure that should you need to store the EQs for any length of time they will be free from damage.

Having experience with a range of Stack Audio products including their LP12 turntable modifications, Link II streamer and of course the AUVA speaker isolators, I had high expectations around build quality and the EQs did not disappoint in this regard. The EQs are manufactured with the same attention to quality as the AUVAs.  Like the AUVAs, the EQs are manufactured from aluminium and use the same absorption material as their bigger siblings.  Whereas the AUVAs contain this material within several internal “cells”, the EQs only use one chamber, I expect this is to reduce manufacturing costs.  As with the AUVAs, if you give the EQs a shake, you can hear the absorption material moving inside.

Another difference in the EQs is the use of what Stack has called a custom Silicone Absorber, or CSA in the base of the EQ.  The  CSA secures the EQ to the equipment shelf and forms a second level of isolation.  The CSA insert is height adjustable and comes in three versions to best suit the weight of the equipment they will be sited under.  Guidance on which type of CSA to order is helpfully explained on the Stack Audio website when making your purchase. 

SET UP AND SOUND QUALITY

Stack Audio recommend that the equipment chassis sits directly on the EQs rather than any existing feet being placed on the EQs so I followed this advice.  I had been supplied with four EQs with level 1 CSVs.  This would be suitable for a load of up 16kg.  For the duration of this review, I used a Pathos Classic One Mkii integrated amplifier which weighs in at 13kg so four EQs with level 1 CSVs were probably just about right.  The EQs can be purchased individually or in sets of three or four so for lighter loads, three would suffice.  For heavier loads, you have the choice of using either three, four or more with higher-level CSVs.  If this seems a bit complicated, it isn’t really and the Stack Audio website will sort out any worries you might have over what you would need to order.

With the four EQs in place, it was time to start listening.  I initially picked a selection of tracks that I had either been listening to a lot recently or that I knew really well from repeated playing over many years.  Also, to assure myself (if not anyone else) that I wasn’t suffering from confirmation bias I took a lot longer with the EQs both in and out of the system than I normally would before writing up my review.  

All of this extended listening allows me to come to the point fairly quickly: if another HiFi manufacturer had not already nabbed the strap line Simply Better then it would be perfectly apt for the EQs; time and again I took them out from under the Pathos and then after a while put them back in again.  Each time the music sounded better with the EQs in the system than when they were not.

“Fair enough” I hear you say “but can you give us some examples?”  I thought you would never ask.  Near the beginning of the title track of Leonard Cohen’s You Want It Darker there is a simple drumbeat overlaid with a bass guitar.  With the EQs in place, there was a percussive thump to the leading edge of the drumbeat that was lessened when the EQs were removed.  Also, with EQs, the drumbeat held its own behind the bass.  Without EQs, it seemed to hide in the bass guitar’s shadow.  This, of course, is just a small detail from a song which features a male choir and a huge, deep close- mic’d vocal from Cohen.  Taken overall, the separation between the instruments (drumbeats and bass), choir, and Cohen’s vocals (quite obviously recorded in a different acoustic space) were more evident and the whole thing just sounded better. 

June Tabor’s Airs and Graces album includes a close-mic’d a cappella version of And The Band Played Waltzing Matilda.   Without the EQs in place, it is possible to hear the physical actions of Tabor forming the words as she sings the song; the tapping of tongue against teeth on the T sounds and the plosive pops of breath on the Ps, not to mention saliva being swallowed between lines.  With the EQs in place, this is all so much more obvious, to a distracting extent perhaps but it does demonstrate quite viscerally the effect that the EQs are having. 

If Leonard Cohen or June Tabor are not your thing, other music is available.  Dubbelstandart’s Chrome Optimism takes Jean Michele Jarre’s Oxygène Part IV and dubs it off into deepest space while Lee Scratch Perry freestyles on top, offering the opinion that “Heaven is very, very high”.  As was he, I imagine, when he recorded it.  As well as deepening the soundstage on this track, the EQs tightened the bass making it easier to discern individual notes without losing any of the seismic power and depth. 

During the period of the review, I kept wondering what would happen if I put the EQs under my Stack-modified LP12 turntable.   The results were not subtle.  The bass frequencies were dramatically reduced, leaving tracks bereft of weight and presence.  On a positive note, the piano on Song of Bernadette from Jennifer Warnes’ Famous Blue Raincoat actually sounded more real and “in the room” than before but at the expense of everything else.  If nothing else though, this experiment proved that the EQs made a difference; a nail in the coffin of expectation bias. 

QUIBBLES

I have thought long and hard about this but I honestly can’t find anything to quibble about with this product and I will explain why below.

CONCLUSION

The EQs are an audio accessory.  In a perfect world, they would be unnecessary because the audio products we spend our money on should deliver optimal performance without any need to resort to tweaks, right?  Experience tells us otherwise though and cables and other accessories carefully matched to a system can offer a series of marginal gains which collectively make the system sound better.  

The improvements offered by the EQs may not be an alternative to an upgraded amplifier or source but they are clearly evident and these products punch way above their price point.  If you have a HiFi system that you are happy with but wonder if adding isolation might make an improvement then I recommend checking the Stack Audio EQs out.  Things might just get even better. If they don’t, Stack Audio offer a 30-day money-back guarantee.  What have you got to lose?

AT A GLANCE

Build quality:

Really well machined with an attractive anodised finish

Choice of silicone inserts to suit a range of applications 

Sound quality:

Increased detail

Tighter bass

Improved soundstage

Value for money:

At £198 for 4 EQs I think these offer ridiculously good value for money

We loved:

Packaging, build quality, performance and price point.

We didn’t love so much:

Nope, I’ve got nothing. 

Elevator Pitch Review: For anyone interested in experimenting with isolation products for audio equipment, the EQs from Stack Audio offer high-level performance enhancement at an entry-level price point (I only went up one floor). 

Price: £198 for four

John Scott

SUPPLIED BY STACK AUDIO