A Tube Legend, Dressed in Midnight

The Unison Research S6 Black Edition is a celebrated pure Class A tube integrated reimagined — more power, a smarter circuit, and a built-in high-resolution DAC, all wrapped in a piano-black lacquered panel and gunmetal finishes. Building on the beloved original S6, this KT77-powered stereo amplifier delivers the rich, harmonically dense, utterly involving sound tube lovers chase, while quietly embracing the digital age. Even Stereophile took notice.

Pure Class A, Refined

The S6 Black Edition runs three KT77 Gold Lion power tubes per channel with two ECC83 signal tubes, in a pure Class A, ultralinear configuration with a 20% tap. Its Cathode Capacitor-Less (CCL) technology removes traditional cathode capacitors and resistors from the signal path, improving low-frequency response and reducing phase shift for a more natural, detailed sound. A seven-section output transformer and improved power management lower noise and boost channel separation. The result is 40 watts per channel — a 15% lift over the standard S6 — with ample headroom and dynamic range.

High-Resolution Digital, Built In

A Sabre ES9018K2M DAC brings modern digital sources into the fold, accepting USB up to PCM 384kHz and DSD256, plus SPDIF and Toslink. Stream hi-res files or spin a CD transport and hear them through the same glorious Gold Lion tube stage that makes your records sing — no separate converter required.

Why You'll Love the S6 Black Edition

• 40W per channel of pure Class A KT77 Gold Lion tube power — 15% more than the standard S6
• Cathode Capacitor-Less (CCL) circuitry for deeper, cleaner low frequencies
• Built-in Sabre ES9018K2M DAC (USB PCM 384kHz / DSD256, SPDIF, Toslink)
• Seven-section output transformer for lower noise and superb channel separation
• Stunning piano-black and gunmetal Italian styling

Frequently Asked Questions

What makes the Black Edition better than the original S6?

More power (40W vs. the standard model, a 15% increase), Cathode Capacitor-Less circuitry for improved low-frequency response, a refined seven-section output transformer, a built-in high-resolution DAC, and elegant piano-black styling.

Does it have a digital input?

Yes. An integrated Sabre ES9018K2M DAC supports USB (up to PCM 384kHz and DSD256), SPDIF and Toslink inputs.

What tubes does it use?

Two ECC83 Gold Lion signal tubes and three KT77 Gold Lion power tubes per channel, run in pure Class A ultralinear mode.

S6 Black Edition Technical Specifications