Holo Audio May — R2R DAC (L1 & L2, made to order)

Dual mono R2R DAC, made to order

Note: because of the nature of this product, the May is not available for online purchase. To order, contact Carlos Moreira: tel. +351 917 230 062, email comercial@myhifihouse.com.

The May is a NOS R2R DAC from Holo Audio, with native DSD1024 and PCM at 1.536 MHz over USB and I2S. It arrived after more than 3 years of development and, according to Holo Audio, has the best measurements of any NOS R2R DAC. It is dual mono: each channel has its own DAC module and its own O-type flat-wire transformer, handmade for this DAC. According to Holo Audio, this transformer type outperformed every transformer it has tested to date, with near-zero leakage. In theory the May can reach DSD2048 and PCM at 3.072 MHz, but this has not been tested yet.

The new linear compensation technology corrects the accuracy errors caused by resistor tolerance and reaches a tolerance of 0.005%. With its own anti-jitter technology, which does not raise the noise floor, the May reaches a SINAD above 115 dB and a dynamic range above 130 dB. The PLL+FIFO system uses a femtosecond VCXO as its clock and a 0.1 Hz third-order low-pass filter against jitter, and it can lock onto 1 kHz signals with high jitter, from 1.5 to 2 µs.

The USB Enhanced module has an FPGA with Titanis 2.0, custom firmware and two XMOS XU208 chips, where the Spring 2 has one. Latency drops to near zero, jitter goes down, the USB eye pattern improves and so does low-frequency performance (-40 dB); Holo Audio quotes 2 to 4 times the performance of the official firmware. The two HDMI-I2S inputs use a custom 4-way circuit instead of the common LVDS chipset. Each line is isolated (MCLK is kept apart from the data lines), which lowers jitter. Each I2S port has a configurable pinout, compatible with most HDMI-I2S devices on the market.

The power supply has multi-stage regulation, with Rubycon ZLH, Panasonic FC and Vishay capacitors, or Holo Audio branded capacitors on the L2 and KTE models. A dedicated circuit greatly reduces the click when switching from DSD to PCM. The front display has larger type than the Spring 2 and smaller than the Spring 1, better contrast and wider viewing angles, and it shows CD track time on the S/PDIF inputs, using data defined in the Red Book standard. The power button is now on the front, and a soft-start circuit prevents blown fuses and pops; the fuse has the same value as on the Spring 1 and Spring 2, despite the two transformers. The CNC-machined aluminium remote control is standard on all three models.

The May has no volume control, by design. For Holo Audio, raising gain, lowering output impedance or converting from unbalanced to balanced are jobs for a preamplifier. If one device's output impedance is too close to the next device's input impedance, the signal gets weak and the analog output degrades. Most DACs with volume control have no integrated preamp, and at this level of quality the brand prefers not to build that degradation into the DAC.

Versions and components

1. Two O-type (not toroidal) flat-wire (not round-wire) audio transformers, 100 VA, 6N copper, handmade (all models)
2. All OCC copper wiring replaced with 1.5 mm pure OCC silver wire, soldered directly to the boards with top-grade audio solder (KTE only)
3. DAC modules hand-selected for better-than-average measurements and higher dynamic range (KTE only)
4. CNC black/copper covers on each DAC module, with laser-etched KTE logos (KTE only)
5. Pure silver, rhodium-plated faston connectors at the IEC inlet (KTE only)
6. Red Nano fuse with gold/silver, graphene and quartz filtering (KTE only)
7. Exclusive KTE capacitors instead of the Vishay caps used on the L1/L2; according to Holo Audio, the improvement over the L1/L2 goes beyond a subtle difference (KTE only)
8. Custom Holo Audio 1000 V 1 µF capacitors, replacing Mundorf EVO silver/gold caps
9. USB Enhanced module with Titanis 2.0 circuit
10. Kitsune Tuned Edition branding inside and out (pure copper Kitsune fox emblem on the top panel) and remote control

Specifications

• Architecture: NOS R2R DAC, dual mono
• DSD: native up to DSD1024 (USB and I2S)
• PCM: up to 1.536 MHz (USB and I2S)
• SINAD: > 115 dB
• Dynamic range: > 130 dB
• Tolerance after linear compensation: 0.005%
• Clock: femtosecond VCXO, PLL+FIFO
• Digital inputs: USB, RCA coaxial, BNC coaxial, AES/EBU, Toslink, 2 x HDMI (I2S LVDS)
• USB: supports Linux, Mac and Windows (7, 8, 10, 2012)
• HDMI I2S: compatible with Singxer SU-2 and Pink Faun I2S Bridge
• Analog outputs: single-ended RCA, balanced XLR
• Volume control: no
• Power: 2 O-type flat-wire transformers, 100 VA, one per channel
• Remote control: CNC-machined aluminium
• Weight: 19 kg
• Dimensions: 430 x 299 x 152 mm