UNISON RESEARCH SH

Pre owned. In excellent condition. Free from any noticeable signs of wear. Without the original packaging.

The Unison Research SH is a headphone amplifier that combines the refinement of tube technology with modern digital capabilities, designed to deliver a high-end listening experience with both analog sources and high-resolution digital audio. Its minimalist two-stage architecture, operating in Single-Ended Class A configuration, employs an ECC83 tube in the input stage and an EL84 tube in the output stage, both connected in triode mode, to produce a sound that is clear, natural, and richly musical. The passive volume control preserves signal purity, while a sensitivity switch allows the amplifier output to be optimized for headphones with different impedance ratings, ensuring outstanding performance even at low listening levels.

The SH features two parallel headphone outputs, making it easy to switch between listeners or share the listening experience without compromising sound quality. Connectivity includes an unbalanced RCA input for any analog source and an asynchronous USB input compatible with USB 2.0 Audio Class, capable of playing PCM files up to 384 kHz and DSD up to DSD128 with resolutions up to 32-bit. The integrated DAC is based on the latest-generation ESS Sabre chipset (ESS ES9010K2M) and incorporates jitter elimination circuitry, galvanic isolation between the USB interface and the conversion stage, and a low phase-noise clock powered by a dedicated "clean" supply section, ensuring highly accurate, detailed, and interference-free playback.

The SH delivers outstanding measured performance, with a signal-to-noise ratio of 110 dB (at 1 kHz, A-weighted, 192 kHz) and total harmonic distortion plus noise (THD+N) of just 0.008% (at 1 kHz, -3 dBFS), confirming its ability to reproduce music with exceptional transparency and dynamic range. By combining classic tube amplification with a state-of-the-art DAC, the Unison Research SH offers a versatile and powerful solution for listeners seeking uncompromising headphone performance with both analog and digital sources, all within a handcrafted component designed for long-term reliability.

Technical specifications:

• USB interface: Asynchronous USB 2.0 Audio Class compatible; supports PCM up to 384 kHz and DSD up to DSD128; resolution up to 32-bit; latest-generation ESS Sabre DAC with jitter elimination circuitry; galvanic isolation between USB interface and conversion stage; low phase-noise clock powered by a dedicated clean power supply; SNR: 110 dB (@1 kHz, A-weighted, 192 kHz); THD+N: 0.008% (@1 kHz, -3 dBFS)
• Maximum output voltage: High sensitivity: 0.5 V/150 Ω; 0.45 V/33 Ω; 0.4 V/10 Ω; Low sensitivity: 1.5 V/150 Ω; 1.2 V/33 Ω; 0.65 V/10 Ω
• Frequency response: -0.1 dB @ 10 Hz; -3 dB @ 50 kHz (Low sensitivity output, 33 Ω)
• Input impedance: 20 kΩ // 100 pF
• Sensitivity: 0.67 V input / 0.33 V output (High sensitivity, 10 Ω); 0.67 V input / 1 V output (Low sensitivity, 33 Ω)
• Input stage: Class A, ECC83/12AX7
• Output stage: Class A, 2 × EL84 connected in triode mode
• Inputs: 1 × RCA line; 1 × USB
• Outputs: 2 parallel headphone outputs
• Feedback: 16 dB
• THD: <0.2% @ 1 kHz, 0.5 V; <0.8% up to 1 V (Low sensitivity output, 33 Ω)
• Power consumption: 45 W
• Dimensions (W × H × D): 225 × 126 × 322 mm
• Weight: 6 kg