The more interesting question of course is what does happen when the Stack Audio feet decouple our components. I see three main advances. First, resolution increases a little mainly in the highs and upper mids. When a hi-hat fades, it seems a bit more finely granulated. The harmonics of an acoustic guitar illuminate more clearly and the same holds true for female vocals as heard on Julie Byrne's album Not even happiness among others. With sonorous male voices like Leonard Cohen, Howe Gelb, Mark Lanegan etc., I didn't hear this. Neither would I claim that electric bass lines came across significantly more defined. And yet for my second point, it did sound different even in the bassment: not fuller or slimmer, drier or richer but spatially more astute. The double bass on Forniquette's eponymous album outlined sharper. It didn't get fatter or more relaxed, just a bit more on point so somewhat more compact and edge limned. Incidentally, this may have been why impulses seemed to place more cleanly. The impact remained unchanged but with the Stack Audio came across more spatially focussed. And this was the case across the frequency spectrum but especially the mids and particularly so on vocals. Without the Auva EQ, images tended to be a little wider, flatter and as if drawn with a softer-tipped pen. The footers increased focus or concentration with more depth and sharper outlines. This higher localization sharpness and 3D imaging was probably the most striking thing about the Stack Audio Auva EQ.

And speaking of 3D, not only did individual images gain depth but so did the entire stage. Pleasantly this didn't happen between the base line and front wall but rather, vocals and centrally mixed instruments came slightly forward. Hence the imagery felt a bit more exciting, forward and at the same time, set against a deeper backdrop. Musicians drawn more clearly had more space at their disposal which ultimately manifested as a more transparent yet tacit stage perception so a clear advantage. As I said at the beginning, the extent of the gains varies by component. I actually put the Stack Audio under my Antipodes music server but couldn't tell a difference. It was different with the BMC Phono that's generally quite insensitive to placement. The difference with/without was most noticeable on my line-level preamplifier. The Electrocompaniet power amplifier and Rockna DAC were in the middle. Of course the more optimized our support surface—I tested this with an additional Phio Audio base—the lower the yield from additional isolators like the Auva EQ. The best thing is to try them out. The right to exchange makes for an easy bridge to cross back on.

For a footer A/B I rummaged through my tool chest of tuning gizmos and found among other things the Stage footers from bFly Audio. In many ways they were similar and here and there even offered a little more resolution while the Stack Audio seemed to be a little more three-dimensional in their imaging. They also differed slightly in terms of tone. Although both decouplers can be considered balanced overall, if you want slightly more aggressive diction in the treble, the bFly Audio are certainly better since the Stack Audio seem more strictly neutral. These differences weren't big and which footer better accommodates us will depend on our system and taste. However, on price a single bFly Audio Stage-1 nearly buys a set of three Auva EQ.

Conclusion. The Stack Audio Auva EQ device isolators are very interesting and inexpensive tuning devices. Tonally they largely leave us alone so nothing shifts towards warmer or cooler, a virtue in already balanced systems. The improvements include slightly higher resolution in the mids and especially treble. Most importantly, the spatial context of the music becomes more tangible and real. This more concrete presentation of recorded space seemed to me the key action of the Auva EQ. The precision and plasticity of individual images increased and the virtual stage expanded. The Auva EQ simply grew more room for a clean front-back layering of the performers. In fact they moved further back and took a step forward. The stage gained in depth though not much in width.

I didn't hear any negatives. Worst case scenario, this tool is ineffective because your component is resistant to resonance dissipation and decoupling efforts; or already too optimized. That's of course possible. Now you can simply return your set whose 30-day money-back guarantee is aggressively promoted. But I suspect that this will be the exception when even with high-quality components there often remains untapped potential when it comes to basic setup. So just give these a try. To personalize, I'm keeping three Auva EQ sets for my own use.

Facts:
Concept: vibration-damping device feet
Design: black-anodized aluminum of 50mm diameter, 28-31mm height adjustable, weight rating from 0-4kg, 4-10kg and 10-15kg all for the same price
Warranty: 3 years