Unison Research SH
Best tube amplifier for audiophiles seeking vintage warmth and digital precision.
Experience unparalleled personal audio with the Unison Research SH Headphone Amplifier. This Italian-crafted amplifier masterfully combines the rich warmth of vacuum tubes with the precision of modern digital audio. Featuring ECC83 and EL84 valves in a pure Class A circuit, it delivers a detailed, low-distortion sound. The integrated ESS Sabre DAC supports high-resolution formats up to 384kHz PCM and DSD128. Enjoy versatile connectivity with RCA and a galvanically isolated USB input, plus dual headphone outputs with adjustable sensitivity for optimal performance with any headphone.
$1999.00
Owner Satisfaction
4.7
/ 5
Category Rank
53
/ 766
#53 in Headphone Amplifiers
Price vs Category Average
+43%
Above average
Input Stage
83127
/ Pure Class A, ECC/AX
Who it's for
- Headphone enthusiasts owning demanding, high-impedance planar magnetic models
- Audiophiles seeking a rich, musical, and non-fatiguing listening experience
- Design-conscious listeners wanting a beautiful, handcrafted centerpiece for their system
Who should skip it
- Budget-conscious buyers looking for more affordable solid-state alternatives
- Users preferring low-maintenance gear that runs cool and efficient
- Desktop users with limited space for bulky audio equipment
Performance breakdown
Sonic Warmth
Pure Class A tube circuitry delivers a lush, organic listening experience.
Digital Precision
The ESS Sabre DAC handles high-resolution files with impressive clinical accuracy.
Headphone Versatility
Adjustable sensitivity ensures a perfect match for diverse headphone impedance loads.
Build Craftsmanship
Stunning Italian design that feels as premium as it sounds.
Signal Integrity
Galvanic isolation effectively eliminates noise for a pristine, silent background.
Connectivity Range
Limited to USB and RCA, lacking balanced inputs for professional setups.
Key Specs
Input Stage
Pure Class A, ECC83/12AX7
Output Stage
Class A, 2 EL84 triode-connected valves
Supported Formats
PCM up to 384kHz, DSD up to 128x
SNR
110dB @ 1kHz, “A” weighted, 192kHz
THD+N
0.008% @ 1kHz, -3dBFS
Weight
6 kg
Dimensions
22.5 cm x 12.6 cm x 32.2 cm
Inputs
1 line RCA, 1 USB
Features
- Pure Class A tube amplification for warm sound
- High-resolution ESS Sabre DAC included
- Dual headphone outputs with sensitivity adjustment
- Galvanic isolation for pristine USB audio
- Low negative feedback for natural sound
- Supports DSD128 and 384kHz PCM
- Elegant Italian design
- Combines vintage tube warmth with modern tech
What customers say
The Unison Research SH amplifier earns high praise for its signature tube sound, consistently described as warm, musical, and richly detailed without listener fatigue. Users appreciate the exceptional build quality reflecting fine Italian craftsmanship and its robust, attractive design, which supports its premium value perception. A major strength is its reliable power delivery, expertly controlling diverse headphones, including high impedance and planar magnetic models, while preserving excellent dynamics. Although costly, owners feel the superb sonic performance justifies the investment for a long-term desktop audio centerpiece. For those seeking lush, emotional depth from a tube design, this unit is considered a top performer.
Know before you buy
The SH utilizes a pure Class A tube circuit with ECC83 and EL84 valves, providing the signature warmth and harmonic richness associated with vacuum tubes. By combining this with a modern ESS Sabre DAC, it achieves a balance of vintage musicality and high-resolution detail.
Yes, the SH features dual headphone outputs with adjustable sensitivity settings. This allows you to fine-tune the gain to match the specific power requirements of your headphones, ensuring optimal performance across a wide range of models.
The USB input is galvanically isolated, which is a significant design feature that prevents electrical noise from your computer or source device from entering the audio signal path. This ensures a cleaner, more pristine sound when listening to digital files.
The internal ESS Sabre DAC is highly capable, supporting PCM audio files up to 384kHz and DSD files up to DSD128. This ensures you can play back high-fidelity digital libraries without needing an external DAC.
With dimensions of 22.5 cm by 32.2 cm and a weight of 6 kg, it is designed as a compact desktop unit. Its elegant Italian aesthetic makes it a sophisticated centerpiece for a high-end personal audio workstation.
As a vacuum tube amplifier, the ECC83 and EL84 valves will eventually require replacement after several thousand hours of use, depending on your listening habits. This is standard for tube-based equipment and allows you to experiment with different tube brands to subtly tailor the sound to your preference.
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