After 3 years of research and development to achieve a whole new level of performance and sound quality, HoloAudio introduces the MAY Level 2 discrete balanced R2R DAC! Flagship of the brand, it offers a simply exceptional and uncompromising design, with the aim of providing the most faithful, musical and accurate sound reproduction possible. It is composed of two distinct blocks, the first corresponding only to the digital / analog conversion system and the second to its dedicated power supply.

The May is a dual mono DAC and therefore has a dedicated DAC module for each channel. Moreover, these are individually powered by flatwire type-O transformers, a model that surpasses all other types of transformers tested: almost zero leakage current, improved dynamics and spectacular overall performance, these are moreover handmade especially for this DAC.

Key features and technologies

HoloAudio May's next-generation linear compensation technology resolves accuracy errors caused by resistor tolerance after compensation, achieving a 0.05% variance in tolerance accuracy. The integrated proprietary anti-jitter system drastically reduces the level of jitter without increasing the background noise or negatively impacting the sound reproduction.

Based on this innovative design, the May is capable of delivering a SINAD of over 115dB and a dynamic range of over 130dB, corresponding to the highest performance that an R2R DAC can achieve today.

The May also takes advantage of the exceptional performance of PLL+FIFO technology for an ever lower jitter level. It uses a high-performance femtosecond VCXO as the PLL clock source.

On the power supply side, the two mono channels of the DAC are independently powered by their own dedicated transformer. An optimized construction allowing a better separation of the channels while limiting the interferences, in order to reveal a wide sound scene.

An architecture that also allows HoloAudio's DAC to natively support, via its USB and I2S inputs, high resolution streams up to PCM 32bit 1536kHz and DSD1024. The two XMOS XU208 USB interfaces use proprietary firmware developed to ensure very low latency and reliable data transmission. The May also features two independent I2S inputs over HDMI, each with an independent 4-channel circuit, making the clock signals less susceptible to interference and jitter than in a conventional LVDS system. Each I2S input can be configured with a different pinout for maximum compatibility.

NOS & OS Modes

The HoloAudio May offers several convenient configuration options. For example, a NOS mode can be activated to cancel any oversampling, with the original data going directly to the converter. This mode may allow for some distortion problems.

On the other hand, the OS mode allows oversampling of the PCM and DSD streams to reach higher frequencies, before digital/analog conversion. The OS PCM mode takes a PCM or DSD stream as input and oversamples it to PCM. The OS DSD mode will take a PCM or DSD stream and oversample it to DSD.

Custom PLL circuit

The May DAC features femtosecond clocks and ultra-high performance discrete voltage regulators. It features an advanced custom PLL (Phase Lock Loop) circuit designed for extremely efficient jitter cancellation. Even the highest jitter levels are almost completely suppressed. The Crystek CVHD-957 VCXO clocks in the device are responsible for recovering the digital signal and reclocking it. However, this function can be deactivated, allowing the performance of this system to be observed. A FIFO buffer allows the clock signals to be stored temporarily, making it possible to avoid using ASRC technology, which would have the effect of altering the audio data.