Formula D/A Converter

Introducing our proprietary Optologic DAC
Class 2.0 USB Audio drivers (only needed in Windows)
Version 1.61b ( certified for Windows 10 ) ZIP >


VAT : IT 08602220967

aqua - acoustic quality  •  Milano  •  Italia

The Formula Dac is the first in the aqua - acoustic quality’s production to show a proprietary D/A conversion system, that we name Optologic Dac. This conversion system follows the same multibit technology (already used in the previous world acclaimed dacs such as La Voce and La Scala) but with a discrete R2R resistors ladder instead of Burr Brown PCM1704 dacs.


Galvanic and magnetic isolations are implemented between the FPGA and the four branches of the R2R ladder converter. This creates complete isolation of all digital circuitry - including the clock - from the analogue section for a pure clean ground plane. It also plays the main role in the differential management of the R2R ladders, achieving perfect symmetry between the counter-phase halves. The result is the highest tonal contrast and naturalness never heard before from digital sources.

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 by extensive use of BJT, Mosfet, Jfet and ultra-fast diodes. Passive parts were selected not just for the best sonic result but also for their top quality, longevity and reliability. With the exception of six superior quality electrolytics, all other caps are Tantalum, solid-polymer OS-CON and double-metalized MJP. The signal path itself is direct-coupled and free of all capacitors. The two output stages (one single-ended, one transformer-coupled balanced) use discrete BJT and JFet with metal-film resistors. All the electronics parts show an ultra low RF noise.
Sample Rates Supported

Asynchronous USB (High Speed)
Digital Receiver
AQlink (I2S bus)
Digital to analog conversion type
Oversampling factor
Analog Conversion method

Digital inputs

Analogue Outputs

Output Impedance
Load Impedance

Frequency Response
Main processor
Control connectors
Front Panel
Power Consumption
Front finish
Case finish
Performance characteristics
AQlink / I2S serial bus  - USB PC Audio : 24 bit / 384 Khz
DSD/64 & DSD/128
S/PDIF - AES/EBU : 24 bit / 192 KHz
Supports DSD via DoP on all inputs
USB Type B
PLL (phase locked loop) technology 128 or 256 FS selectable
LVCMOS level
Proprietary Optologic DAC
Pure R2R ladder - FPGA (Field Programmable Gate Arrays)
based digital decoding without digital filter
- RJ45 AQlink (I2S serial bus) - 24 bit / 384 KHz - DSD/128
- BNC coax (S/PDIF) 75 Ohm  -  24 bit / 192 KHz - DSD/64
- USB port  -  24 bit / 384 KHz  - DSD/64 & DSD/128
Modular input:
- AES/EBU balanced 110 Ohm -  24 bit / 192 KHz - DSD/64
- RCA coax (S/PDIF) 75 Ohm -  24 bit / 192 KHz - DSD/64
- AT&T (ST Fiber) -  24 bit / 192 KHz - DSD/64
- Optical TOSLINK -  24 bit / 96 KHz
UNBAL 2 RCA Output 2.4 V RMS
BALANCED ( passive transformers symmetrical ) 2 XLR Output :
3.8V RMS
10 Ohm RCA - 600 Ohm XLR
10 kOhm (min.) RCA - 600 Ohm XLR
20Hz to 22kHz +0.5dB/-0.5dB
<0,016% 1KHz -10dB
STM-ARM microcontroller
RS-232 D-SUB 9-pin connector
Power, phase invert, mute, input switch, RC5 remote sensor
100-115V / 220-240V; 50 or 60Hz - 82VA
( W x D x H ) 450 x 380 x 100 mm
9 kg
Satin Alu Silver or Satin Black
Grey Nextel powder coated
Owner's Manual >

• Formula DAC 6MOONS Blue Moon Award
"With the original La Scala 2 being one of my two reference converters and the top deck in contributor John Darko's DAC index, exploring audible space beyond it seemed, truth be told, a rather tall order. How much room was there left for improvement? What ungodly reference gear would it take to hear it? As it turned out, the Formula delivered a demonstrable lead with €6'500-class ancillaries like a Pass Labs XA30.8 or pair of Zu Audio Druid V speakers. If you're an audio aboriginal who goes deep walkabout into gargantuan soundstages to cherish size, scale and utmost specificity about recorded space, this Italian formula has your number. But it's not merely about the usual 3D markers and how precisely and widely spaced they are. It's about an added dimension. That accesses the emotional mood or climate of the playback scenery. Whilst costlier decks came through earlier, none of them did it at that potency. Granted, to fully matter relies on superior recordings. Lesser or purely synthetic efforts reveal that they lack that particular magic. Finally there's this peculiar easy-digital aspect as though your brain's usually active aural processor went on holiday because it's not needed. As such, I must highlight Aqua Hifi's Formula with one of our sparsely administered awards. True, it's serious money. But it's seriously well built. And it delivers very serious performance. Yet all this multi-stage seriousness melts away when one is faced by such deep holistic listening satisfaction. That's what the 'high' in hi-end should be all about. Cachet, pride of ownership, resell value and bling to impress the ignorant with all factor. But they pale to nothing against delivering the actual experience. The Formula does. So it pays to study its recipe in detail. It really is something else."

Srajan Ebaen