Holo Audio May Review - Part 1 - Going the extra mile

Summary

This in-depth review explores the Hollow Audio May DAC, emphasizing its extraordinary engineering and design. The reviewer highlights the device's massive, solid build, luxurious materials, and meticulous attention to detail. Key technical features include a proprietary USB implementation, galvanically isolated digital inputs, an advanced PLL for jitter reduction, a true R2R ladder with linear compensation, and a native 1-bit DSD converter. Both level 2 and level 3 models are examined, with minor differences noted. The review focuses on objective performance, internal components, and design excellence, promising a follow-up part discussing subjective listening impressions and comparisons, underscoring the product’s over-the-top, perfectionist approach to audio engineering.

Takeaways

• 😀 The reviewer emphasizes complete independence from manufacturers and affiliate links, ensuring honest opinions.
• 😀 The Hollow Audio May DAC is extremely large and heavy (~20 kg / 45 lbs), requiring substantial space for placement.
• 😀 Build quality is exceptional, featuring black brushed aluminum, copper buttons, copper side panels, and a CNC-milled remote.
• 😀 The power supply is dual-mono with O-type hand-wound transformers, linear multi-stage regulation, and voltage switchable for regions.
• 😀 The DAC includes a proprietary USB implementation, fully galvanically isolated, offering extremely low jitter performance.
• 😀 Hollow Audio uses a powerful PLL to attenuate jitter (>80 dB), enabling clean audio from noisy sources.
• 😀 The main DAC is an R2R ladder with FPGA control, complemented by a fully discrete 1-bit native DSD converter for DSD1024 playback.
• 😀 Linear compensation technology measures every component in real-time for optimal performance and dynamic range.
• 😀 Analog output is fully discrete, Class-A, direct-coupled, and capable of XLR and RCA outputs, running hot and consuming ~50W at idle.
• 😀 I/O includes configurable I²S, coaxial, BNC, AES, optical, and USB inputs, allowing complete pinout customization for compatibility.
• 😀 Oversampling and NOS options allow flexible audio processing, while the front panel provides power, mute, and source selection.
• 😀 The review is split into two parts, with Part 2 covering subjective listening impressions and Level 2 vs Level 3 KTE DAC comparisons.

Q & A

What is the reviewer's approach to affiliate links and product reviews?

The reviewer avoids affiliate links entirely, ensuring unbiased opinions. Positive feedback is based on genuine appreciation of the product, not incentives from manufacturers or traffic-driven affiliate marketing.

How heavy is the Hollow Audio DAC, and what implication does this have?

The DAC weighs around 20 kilograms (45 lbs), making it too large for a casual desk setup. Its weight reflects the robust build quality and the substantial internal components.

What is unique about the Hollow Audio power supply design?

It features dual-mono, linear multi-stage regulation, hand-wound O-type transformers with flat wire, and complete galvanic isolation to minimize electromagnetic interference and noise.

How does the Hollow Audio DAC handle USB input differently from standard DACs?

It uses a fully proprietary USB implementation with galvanic isolation and extremely low jitter, ensuring no electrical noise passes from the source to the DAC.

What are the main components of the DAC's internal architecture?

The DAC includes a fully balanced R2R ladder controlled by an FPGA, a separate true 1-bit native DSD converter for high-resolution DSD playback, and a fully discrete Class A analog output stage.

What is Linear Compensation Technology in the Hollow Audio DAC?

It is a system where every component and trace is measured, and real-time corrections are applied to maintain optimal performance, ensuring exceptional accuracy for an R2R DAC.

How does the DAC manage DSD playback?

It uses a separate native 1-bit DSD converter instead of converting DSD to PCM, supporting extremely high sample rates like DSD1024 and PCM 1.536 MHz for maximum fidelity.

What measures are taken to reduce jitter in digital inputs?

The DAC features galvanic isolation on all digital inputs, a powerful phase-locked loop (PLL) that attenuates jitter by over 80 dB, and a proprietary I²S implementation to maintain signal integrity.

What differences exist between Level 2 and Level 3 KTE editions?

Level 3 includes upgrades like silver wiring in the power supply, CNC-milled logos on the chassis, and minor design refinements, though performance differences are minimal.

How does the DAC handle temperature and power management?

The Class A output stage runs hot and consumes around 50W at idle. The DAC regulates its temperature to remain optimal, and the mute button disables output without significantly reducing power consumption.

What is the purpose of the proprietary I²S circuit?

It allows complete flexibility in pinout configuration, ensuring compatibility with different devices and reducing jitter, unlike standard LVDS I²S implementations.

What is the reviewer’s overall impression of Hollow Audio’s engineering philosophy?

The reviewer praises Hollow Audio for a perfectionist, over-the-top approach that avoids shortcuts. Every aspect of the DAC is over-engineered to achieve the highest possible technical performance.