The legendary Spring (Asterion), essential reference for R2R conversion circuits, returns in a largely optimized version with femtoclock clock, modified interfaces and a whole new structure of resistance network offering exceptional measurements.

HoloAudio is a true masterwork of digital to analog conversion. It uses two different circuits (R2R DAC) to work separately with DSD and PCM signals in order to make the most of both technologies without compromising audio quality. Its DSD exclusive circuit makes it the very first R2R DAC supporting native DSD without any conversion or modulation.

This version integrates an impressive panoply of heavily modified I / O interfaces to work in line with the hardware reality of the device and get the best audio performance. Such as a quad-circuit I2S interface as well as a USB interface controlled by femtoclock clock with exclusive firmware offering performance 2 to 4 times superior to standard XMOS U208 algorithms.

The Spring II has an oversized power circuit with digital and analog circuit isolation to deliver exceptionally clear sound with a noise level below 0.2uV over the entire 100kHz band.

SPRING II version Level 2

Review by Audio Science Review

R2R Dual Circuit

The digital to analog conversion stage consists of a double resistance network (R2R DAC).

The first network is an R2R circuit optimized for multibit signal conversion (PCM) accompanied by an auxiliary dynamic compensation network. This redundancy makes it possible to overcome the limitations induced by the tolerance of the componentsand reach a level of precision that would otherwise require resistors with a tolerance of 0.00005%!

The network sercond is also an R2R circuit optimized for the digital to analog conversion of signals encoded on one bit (DSD).

This technology, specially developed for the Spring II, has been soberly called "Vector Step Resistor Network" by Holo Audio. Its principle consists in dimensioning the resistance network in order to allow it to convert the signal in real time. Le circuit
The DSD circuit thus avoids any form of memory buffering or multi-bit signal pre-conversion technique that may otherwise cause additional modulation and affect the timbre of very high definition audio files.

The Spring II is able to exploit all the advantages of the DSD format without any compromise on fidelity, a unique feature to date.

Each of these two resistance networks is mounted in a fully balanced structure with positive on the upper face of the PCB and negative on the lower face to increase accuracy without increasing the size of the case.

Mode Oversampling & Non-Oversampling

The firmware integrates various sampling modes to offer a flexible conversion solution that will easily adapt to your audio installation.

• Mode NOS (no oversampling and direct conversion of the digital stream).
• Mode OS (oversampling of PCM and DSD signals at the highest frequency before converting digital to analog).
• Mode OS PCM (automatic PCM conversion before D/A conversion, regardless of the type of input signal).
• Mode OS DSD (automatic DSDconversion before D/A conversion, regardless of the type of input signa).

Input Connectivity

The input panel offers all the necessary connections to deal with any integration scenario.

There is an AES / EBU entry, a coaxial S / PDIF input on RCA connector as well as a coaxial input on BNC connector. A Toslink Optical S / PDIF connector is also available. These inputs support sampling from 44.1 to 192kHz - 24bit (PCM) and DOP64 (DSD).


The I2S input on HDMI connector conforms to the LVDS HDMI standard (Audio-GD, Singxer ...). This input is compatible with the sampling frequencies from 44.1kHz to 1,536M - 32bit (PCM) / DOP64-512 / DSD64-1024 (DSD native).

The Spring II also has a USB input with galvanic isolationand native support for digital streams up to DSD1024 and PCM1.536M. This feature allows the Spring II to offer two inputs compatible with the extreme sampling frequencies., when most of the very high-end DACs only have an I2S input -less standard - for this purpose.

Output Connectivity

The DAC Spring II L2 offers a balanced analog stereo output on 3-pole XLR connector as well as a single-eded analog stereo output on RCA connector.

The output stage operates entirely in pure class A.

It is a pure DAC (no volume control or attenuation). The outputs must therefore be connected to a preamplifier, an integrated amplifier or active speakers with adjustable attenuation.