S6 vs Quad II Classic
The II Classic's power @ 8ω is 25W against the S6's 35W, its output impedance 8Ω against 6Ω, and its weight 19.1 kg (42 lbs) against 25 kg (55 lbs). Both share class (A).
AI-generated product photo — not official manufacturer imagery.
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Estimated price (community-sourced)
$2,400 - $5,995
Around — community and catalog average, updates slowly
About the S6
The Unison Research S6 is a high-quality stereo integrated valve amplifier featuring a single-ended parallel ultralinear output stage with 3 EL34 pentodes per channel and 2 ECC83 triodes in the preamp stage. It operates in pure Class A, delivering 30 to 35 watts per channel with a frequency response from 20 Hz to 50,000 Hz. The amplifier is designed with a minimal number of components in the audio path to preserve sound purity and features handcrafted wooden front panel inlays and stainless steel rotary controls. It includes 5 line inputs and 1 tape output, with an output impedance of 6 Ohms and input impedance of 47 kOhms. The S6 weighs 25 kg and measures 35 cm x 21 cm x 49 cm. It is praised for its detailed, dynamic sound with warmth typical of valve amplifiers, and its ability to drive a wide variety of speakers, including low sensitivity models. The amplifier is made in Italy and consumes up to 265 VA of power.
Specifications
Power Specifications
Amplification power output and characteristics
- Power @ 8Ω
- 35W @ 8Ω
- Amplifier Class
- A
- Minimum Impedance
- 6Ω
- Input Impedance
- 47000Ω
Analog Output
Analog signal output specifications
- Output Impedance
- 6Ω
Connectivity
Input and output connections
- Analog Inputs
- line
- Analog Outputs
- tape
Physical Dimensions
Size, weight, and appearance
- Dimensions
- 350 × 210 × 490 mm (W × H × D)
- Weight
- 25 kg (55 lbs)
Key Specifications
Power: 35W
Frequency: 20-50000 Hz
Specifications are community-contributed and may not be accurate or complete. Verify all details with the manufacturer before making purchasing decisions. Terms & Conditions