Reviewer: Srajan Ebaen
Financial interests: click here
Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo boost, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 12.2), PureMusic 3.02, Qobuz Hifi, Tidal Hifi, Fore Audio DAISy1, COS Engineering D1, Aqua Hifi La Scala MkII, Metrum Hex, AURALiC Vega
Preamplifier: Nagra Jazz, Esoteric C-03, Vinnie Rossi LIO (DHT module)
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1, F5, F6, F7; S.A.Lab Blackbird SE; Crayon Audio CFA-1.2; Goldmund Job 225; Gato Audio DIA-250; Aura Note Premier; Wyred4Sound mINT; AURALiC Merak [on loan]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; Sounddeco Sigma 2; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Druid V & Submission; German Physiks HRS-120; Eversound Essence
Cables: Complete loom of Zu Event; KingRex uArt, Zu and LightHarmonic LightSpeed double-header USB cables; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Arkana Research XLR/RCA and speaker cables [on loan]; Sablon Audio Petit Corona power cords [on loan], Black Cat Cable redlevel Lupo
Power delivery: Vibex Granada/Alhambra on all components, 5m cords to amp/s + sub
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands [on loan]
Sundry accessories: Acoustic System resonators
Room: 5.5 x 15 metre rectangular space with double-high vaulted ceiling and stone-over-concrete flooring
Review component retail: $13'800

. When a brief press release made the rounds that Aqua Hifi were about to bow their new flagship DAC during an April 9th 2016 dealer event in Belgium, it revealed nothing but the Formula name. Putting on my pointiest hat, I wondered. Had Aqua's established preference for R2R conversion finally clashed with native DSD demand? Did they mint a dual-engine machine that would auto-switch depending on signal format? Whilst some might call that pandering to fashion, others would call it smart business. Next a teaser photo emerged. It showed sample-rate indicators up to 384kHz but no DSD. Clearly Stefano Jelo & Cristian Anelli hadn't succumbed to DirectStream. Brava.

That begged a question. What was optologic? Opto couplers aren't uncommon. They can isolate circuit stages and remove a ground connection. Toslink or glass fibre cables conduct electrical signal converted to light to accomplish something similar. Light-dependent resistors show up in attenuators from Tortuga Audio and Constellation Audio. Light-based tech also plays centre stage in Siltech's Saga electronics where "an incredibly powerful light source drives a photo-electric cell to generate DC for the amplifier output stage, galvanically isolating and fully decoupling the current gain stage from the AC supply". Light factors in infrared remotes and with optical drives from CD to DVD to BluRay.

On the face of it, none exactly explained an optological DAC. Aqua aqa Acoustic Quality weren't known for taking marketing liberties. Instead, our Italians had gained renown for fairly priced very well-done converters using mature no-nonsense tech with solid execution. The previous LaScala MkII flagship with tube outputs remains one of my reference machines. It went without saying. Had it just been summarily dethroned, the new formula had to be a winner. Prior to the full reveal, its ingredients simply remained mysterious.

A week later, Cristian Anelli sent a prelim Italian tech PDF. He calling it a work in progress. This was confirmed by the text suddenly interrupting. Of what was there, Google translator made the following: "Galvanic and magnetic isolation are implemented between the FPGA and the four branches of the R2R ladder converter. This not only creates complete isolation of all digital circuitry including the clock from the analogue section for a pure clean ground plane. It also plays a vital role in the differential management of the R2R ladders, achieving perfect symmetry between the counter-phase halves. The result is high tonal contrast and naturalness not heard from digital machines. The Formula DAC uses no digital filter or any other compensation, relying instead on maniacal attention to each sub circuit. The analog and digital power supplies are executed purely discrete and with BJT, Mosfet, Jfet and ultra-fast diodes. Passive parts were selected not just for sonics but top quality, longevity and reliability. Except for six extreme-quality electrolytics, all other caps are Tantalum, solid-polymer OS-CON or double-metalized MJP. The signal path itself is direct-coupled and free of all capacitors. The dual output stages—one single-ended, one transformer-coupled balanced—use discrete BJT and JFet with metal-film resistors. All parts are characterized by very low RF noise..."