Aqua Hifi to premiere Discrete R2R DAC module for La Voce S3 at AXPONA


I love Italy, and I love the sound of older DAC chips, and also R2R ladder DACs, but I’m part Italian so I guess I come by the first part naturally, the second has grown from personal experience. So, when the good people at Aqua Hifi sent me a note about their Acoustic Quality R2R DAC module upgrade, I wanted to share that news here.

I’ve heard the Aqua gear at several shows, and always enjoyed the warm, full sound that never seemed to sacrifice resolution for timbre, and tone, so I can only imagine that the impact on the musicality of Aqua products featuring the new discrete R2R DAC module is not of a subtle nature. Since I’ll be in Chicago, I’ll let you know what I hear there.

–Rafe Arnott

 Press release below:

Owners of original La Voce can upgrade to La Voce S3 Discrete DAC. The update for the La Voce units of existing owners consists of the following hardware / firmware modifications:
1. FPGA / decoding board cod. P608, high-resolution up to 384kHz PCM and DSD128
2. R2R Ladder resistors board cod. P607
3. USB board cod. P901 with new firmware
4. hardware modification of main board P601
5. hardware modification of I2S / USB board P603

For the latest information about the La Voce S3 Discrete DAC, contact your local aqua – acoustic quality representative.

About the S3 Discrete DAC:

By combining dedicated research with creative thinking, our research and development has brought forth a range of innovation aimed at recreating the experience of live music.
• Proprietary Optologic R2R system with galvanic isolation and fully decoupling ladder DAC • Discrete R2R ladder DACs with low noise precision resistors
• High performance proprietary FPGA-based digital decoding without digital filter
• Proprietary hybrid 2-stage XMOS xCore XE216 + FPGA

• Exclusive high-performance digital interface AQlink (I2S protocol), uncompromising digital connection from transport unit to DAC, employs CAT6 cable can connect both RJ45 and professional etherCON RJ45

• proprietary ISDC (Isolated Synchronous Discrete Circuit) digital decoding and clock manager

• High-performance AQ Discrete Regulator (MOSFET, J-FET, BJT) for analog and digital DAC’s power supply

• MODULAR DESIGN with upgradeable multi board platform

It has always been aqua’s singular focus to produce the very best digital to analogue converters and digital sources (La Diva) possible.

Today, the product line includes three DAC models (La Voce S3, La Scala MKII Optologic, Formula xHD) and one CD transport (La Diva).

Our mission is to build electronics able to create the emotional connection one experiences with live music.

In our view, this can only be realized by submitting every individual component to a series of listening tests.

This philosophy has driven the design of all of aqua’s products, culminating in the choice of Non- oversampling R2R ladder conversion technology.

The FORMULA xHD has a 24bit sign-magnitude ladder converter. We believe this is the best conversion technology especially for low level signals.

This requires not two but four 24 bit resistors banks, each one made of very low tolerance discrete resistors.

The precision R2R ladder network for each channel is also galvanically and magnetically isolated from the FPGA by way of opto-couplers which is why we call this system “Optologic.”

This creates complete isolation of all digital circuitry – including the clock – from the analogue section, for a clean, noiseless ground plane. This is also critical 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.

At the output of the R2R ladder there is a Class-A discrete transistor buffer.

The absence of digital filtering means no processing of the input signal. The original digital samples are translated to the reproduced sound, preserving the transient shape and avoiding any ringing.

In this way we also avoid the “intersample overs” problem that is vital to faithful reproduction, considering current recording studio practices.

With our R2R conversion technology the sound is natural, fast, dynamic, and without the sense of compression characterizing others converters. We could say that our effort at Aqua is to obtain a sonic result comparable to that produced by a studio master reel-to-reel recorder.

For aqua being able to reproduce the precise temporal response, dynamics and harmony of sound far outweighs technical measurements. After all, achieving “analog sound” is what matters most.

The Formula is also able to reproduce DSD tracks (DSD64, DSD128, DSD256). For DSD we developed our own proprietary digital processing circuit that is resident in the FPGA code.

As explained before, the Formula xHD DAC uses no digital filtering or any other compensation, instead we rely on maniacal attention to each sub-circuit.

The separate analog and digital power supplies are executed purely by extensive use of discrete BJT, Mosfet, J-Fet 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 electrolytic capacitors, all other caps are Tantalum, solid-polymer OS-CON and double-metalized MKP.

The signal path itself is direct-coupled and completely capacitor-free.

The two output stages (one single-ended, one transformer-coupled balanced) use discrete BJT and J-Fet with metal-film resistors. All the electronic parts produce ultra-low RF noise.

We are continuously experimenting and open to new discoveries which is why our machines are modular and upgradable to accommodate future technology.


Key features:


• R2R resistor ladder network D/A conversion

• High performance proprietary FPGA-based digital decoding without digital filter

• Jitter free digital interface AQlink (I2S protocol), uncompromising digital connection to La Diva cd transport

• Zero S/PDIF Jitter design, digital receiver stage PLL (phase locked loop) technology

• Discrete Regulator (MOSFET, J-FET, BJT) for analog and digital DAC’s power supply

• MODULAR DESIGN with upgradeable multi board platform

• 2 separate low noise transformers, one for the analog and one for the digital section

• Fully discrete analog stage
• Electronically-balanced XLR outputs

Performance characteristics

• Proprietary USB Firmware / driver :
Apple MAC OS – Linux OS : USB asynchronous native support, no need to install drivers software

• Fully upgradeable high-speed USB Audio Class 2 module, PCM 44.1kHz to 384kHz PCM up to 24 bits, DSD64 / DSD128, operates with computers running OSX 10.7 and above, WINDOWS 10, 7, 8, XP with ASIO bit perfect

• Digital phase selector on front panel

• High-quality parts selected for sound quality: – 105° long life capacitors
– low noise Metal Foil ultra-precision resistors – metallized film pulse capacitor

– ultra-fast diodes

• Analog output: RCA single-ended – XLR balanced asymmetrical

• Aluminium anti-resonant cabinet with Nextel • Designed and handmade in Italy

La Voce to the next level

Digital to analog conversion type

Proprietary Discrete DAC
Pure R2R ladder – FPGA (Field Programmable Gate Arrays) based without digital filter

Supported Native Sample Rates

AQlink / I2S serial bus – USB PC Audio : 44.1kHz to 384kHz PCM up to 24 bits
DSD64, DSD128
Supports DSD via DoP on all inputs

DAC architecture

Multibit sign magnitude R2R ladder (upgradable)

Asynchronous USB (High Speed)

USB Audio Class 2 with Type B connector

Digital Receiver

PLL (phase locked loop) technology 128 or 256 FS selectable

AQlink (I2S bus)

LVCMOS level

Oversampling factor


Analog Conversion method

Pure R2R ladder – FPGA (Field Programmable Gate Arrays) based digital decoding without digital filter

Digital inputs

– RJ45 AQlink (I2S serial bus) – 24 bit / 384 KHz
– BNC coax (S/PDIF) 75 ohm – 24 bit / 192 KHz
– USB port – 24bit / 384 kHz PCM – DSD64, DSD128
AQ-i modular input:
– AES/EBU balanced 110 ohm – 24 bit / 192 KHz (cod. D111) – RCA coax (S/PDIF) 75 ohm – 24 bit / 192 KHz(cod. D113)
– AT&T (ST Fiber) – 24 bit / 192 KHz(cod. D112)
– Optical TOSLINK – 24 bit / 96 KHz (cod. D114)

Analogue Outputs

UNBAL 2 RCA Output 2.4 V RMS
BALANCED (asymmetrical output) 2 XLR Output : 4.8V RMS

Output Impedance

100 Ω RCA – 600 Ω XLR

Load Impedance

10 k Ω (min.) RCA – 600 Ω XLR

Frequency Response

20Hz to 22kHz +0.5dB/-0.5dB


<0.1% 1KHz -20dB

Front Panel

Power, input selector, Phase Invert switch

Power Consumption

100-115V / 220-240V; 50 or 60Hz – 58VA


( W x D x H ) 450 x 310 x 100 mm


7 kg

Front finish

Satin Alu Silver or Satin Black

Case finish

Grey Nextel powder coated

About Rafe Arnott 389 Articles
Editor of InnerFidelity and AudioStream


  1. Does this kill the ability to use the TDA1541A, AD1865, and PCM1704 modules? Please ask.

  2. A wonderful company to work with. Using their Formula x HD DAC and La Vida transport. Well worth an audition.

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