Country of Origin
Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Sonoma 14), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Singxer SU-6 USB bridge, LHY Audio SW-8 & SW-6 switch, Laiv Audio Harmony and Sonnet Pasithea; Active filter: Lifesaver Audio Gradient Box 2; Power amplifiers: Kinki Studio EX-B7 monos & Gold Note monos on subwoofer; Headamp: Kinki Studio THR-1, Enleum AMP-23R, aune S17Pro Evo; Phones: Raal 1995 Immanis; Loudspeakers: Qualio IQ [on loan] Cables: Kinki Studio Fire, Furutech; Power delivery: Kinki/Vinshine Tai Hang on amps, Furutech GTO 2D NCF on low-level gear; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 6 x 8m with open door behind listening seat; Room treatment: 2 x PSI Audio AVAA C214 active bass traps
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to COS Engineering D1 DAC/pre; Filter: Lifesaver Audio Gradient Box 2; Amplifier: Kinki Studio EX-M7; Headamp: Cen.Grand Silver Fox; Loudspeakers: MonAcoustic SuperMon Mini + Dynaudio S18 sub, sound|kaos Vox 3awf, Albedo Aptica; Power delivery: Vibex Granada/Alhambra, Akiko Audio Corelli; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~3.5 x 8m
Desktop system: Source: HP Z2 work station Win10/64; USB bridge: Singxer SU-2; DAC: iFi Pro iDSD Signature; Speakers: DMAX P61; Headphones: Final D-8000 & aune SR7000 Audeze LCD-XC
Upstairs headfi system: FiiO R7; Headphones: Meze 109 Pro, Fiio FT3, Raal 1995 Magna, HiFiMan Susvara
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: ~€1'200/8 [exact pricing contingent on the day's currency conversion from UK pound to euro]
Particle impact accelerator? Hifi isn't rocket science. Neither is Theo Stack's concept of vibration isolation for speakers, components or as spinning vinyl stabiliser. All models use variations on a golf course's sand trap. Huh? Unlike a tennis court and its balls tweaked for maximum bounce, a sand trap absorbs an incoming ball's considerable kinetic energy which can top out at 290km/h. The shearing forces of friction between loose grains of sand convert this motional energy to heat. No bounce. Unlike roller-ball or wire-suspended isolators, Theo's solid footers don't incur lateral motion. Unlike elastic rubber absorbers, there's no vertical give or spring action either. Theo's Auva come in three sizes depending on number of internal chambers and amount/type of particle fill like powdered tungsten. They all support up to 275kg. That can even service full-blown equipment racks as floor interface without any concern over weight matching as we apply to viscoelastic types. Unlike them too, we don't fret over lost compliance aka eventual material fatigue. Auva tops sport a threaded M8 receiver. The undersides carry hard felt to protect hardwood, tile, brick or stone flooring whilst the optional spikes shown will penetrate carpet to meet the sub floor. Pricing for sets of 8 spans ~€530 to €1'500. As a direct-selling UK outfit, 'continental' shipments depart from within the EU to avoid post-Brexit customs pain. Particle impact accelerator? It's not Geneva's subterranean CERN colliding atoms. It's Auva where mechanical vibrations hit strategic pockets of loose particles to be converted to heat. It's not rocket science, just good common sense, honest engineering and direct sales. My Berlin colleague Ralph Werner already covered this ground last year in its EQ version for components. Now I'm playing 2nd fiddle – um, opinionator by looking at stand-mount monitors, floorstanders and subwoofers with Auva versions dedicated to that purpose.
Can one isolate another way? Sure. Canada's IsoAcoustics work with already 30 brands on an OEM basis. At Munich HighEnd 2025 they ran A/B comparisons between spiked and isolated loudspeakers. For impressions of that demo, go here. Magico and Wilson have their own takes on constrained-layer damping whereby footer materials of differing hardness and resonant behaviour get strategically combined and bonded to cancel each other out. There's wire suspension from Boenicke to sound|kaos and Wellfloat; ball-bearing types from Ansuz to Hifistay; and a mix of viscoelastics and bearings à la Carbide.
Regardless of method or implementation, what they all share is the transfer interruption of speaker-generated mechanical vibrations into the floor to avoid structural resonances; and to isolate the speakers from such floor-migrating resonances. It's about less noise so more signal. We must decide on the method, looks, size and price. With speakers in particular, proper tweeter alignment can be crucial. If we replace stumpy stock spikes with high-rise aftermarket isolators, we might need to change the speaker's rake so the tweeter axis returns to ear height.
If we move speakers about regularly—perhaps to pull them out during listening or to hoover behind them—we might want footers that slide easily and bolt securely. If we have plush carpet, a spike option like Stack Audio's could be mandatory. If we suffer uneven flooring, height adjustments are key.
So there are considerations other than sonics. At the end of the day given their lowly MO—on the floor, possibly out of sight or mostly—a happy sticker could be paramount to having more listeners explore this critical if mostly overlooked interface. €3.5K as Ansuz demand for a single Darkz Z2S footer will derail all but industrials, stock brokers and crypto scammers. In this product category of hifi tweaks, we want less cryptic not more.
With Theo lining me up for two quads of Auva 70 so his middle model, the industrial damage is ~€150/ea. Only DIYers claiming that they can do all the R&D then machining and sourcing of the particle compounds for less will call that a scam. Weaker wallets can always look at the Auva 50 which comes in at ca. €67/ea. [The above photo of a static show exhibit nicely illustrates the size difference of the three Auva models for speakers and subs.]
