THÖRESS EHT Hybrid Triode Mono Amplifier (Pair)

The THÖRESS EHT Hybrid Triode Mono Amplifier (EHT Monoblock) represents a radical yet purist approach to amplification, designed to bridge the gap between the emotional engagement of single-ended triodes and the driving capability of solid-state technology. "EHT" stands for EINTAKT-HYBRID-TRIODE (Single-Ended Hybrid Triode), a proprietary topology developed by Reinhard Thöress. Unlike typical hybrid designs that simply marry a tube preamp to a standard Class AB output stage, the EHT Monoblock utilizes a single-ended triode gain stage followed by a unity-gain MOSFET output buffer. This unique configuration allows the amplifier to deliver the harmonic richness and texture of a vacuum tube while providing the high current and damping factor necessary to drive difficult loudspeaker loads with absolute authority.

Key Features:

• EHT Topology: A unique Single-Ended Hybrid Triode circuit combining a vacuum tube voltage gain stage with a unity-gain MOSFET current buffer.
• Class-A Operation: Runs in pure Single-Ended Class-A mode for zero switching distortion and ultimate linearity.
• Tube Complement: Utilizes highly linear 6J5GT (or 7A4) and 12HG7 vacuum tubes for voltage amplification and driver duties.
• Zero Global Feedback: Designed without any global negative feedback to preserve the natural dynamic structure and phase integrity of the music.
• High Damping Factor: Low output impedance ensures excellent control over loudspeakers with low efficiency or critical impedance curves.
• Adjustable Gain & Bass Boost: Features a 6-position rear rotary switch for on-the-fly gain adjustment and subtle bass equalization.
• In-House Transformers: Equipped with ultra-low noise, hand-wound C-Core mains transformers produced in-house by THÖRESS in Germany.
• Point-to-Point Wiring: Meticulous hand-construction using air-wiring techniques for the shortest possible signal paths and long-term reliability.

The EHT Concept: Purity and Power

The philosophy behind the EHT Monoblock is to allow the vacuum tube to do what it does best—amplify voltage—while relieving it of the burden of driving the loudspeaker load. The voltage gain is handled entirely by a single-ended triode stage (typically a vintage 6J5GT or 7A4 type), chosen for its exceptional linearity. This signal is then handed off to a unity-gain MOSFET output stage.  Because the MOSFETs provide only current amplification (buffering) without adding voltage gain, the sonic signature of the amplifier remains dominated by the single-ended triode, yet it possesses the muscle to deliver up to 50 watts into a 4-ohm load with rock-solid stability.

Ultimate Flexibility

Recognizing that system matching is critical, THÖRESS has equipped the EHT Monoblock with a unique 6-position rotary switch on the rear panel.  This allows the user to adjust the input sensitivity (gain) in precise steps, ensuring optimal compatibility with a wide range of preamplifiers and loudspeaker efficiencies. Additionally, specific positions on this dial engage a subtle, active bass boost. This feature is implemented without sound-degrading tone control circuitry, allowing users to restore tonal balance in rooms that swallow low frequencies or to flesh out the bottom end of lean-sounding speakers.

Vintage Aesthetic, Modern Engineering

Visually, the EHT Monoblock pays homage to professional laboratory equipment from the golden age of audio. The chassis is constructed from non-magnetic aluminum with a distinctive powder-coated finish and anodized printing  Despite its retro looks, the internal engineering is state-of-the-art, featuring high-grade electrolytic capacitors made in Germany, vibration-isolated transformers, and a layout optimized for low noise and thermal stability. It is a "forever component," built to provide decades of musical enjoyment.

The Listening Room Difference

We’re a third-generation family business with a brick-and-mortar showroom in Chestertown, Maryland, and a reputation built on trust, not hype. Whether you’re visiting in person or ordering online, we bring decades of experience, personalized service, and honest guidance to every interaction. We don’t just ship boxes. We help build systems, answer your questions like real humans, and make sure every detail of your setup is right, from the cables to the final connection. Our passion is helping you get the most out of your gear, with support that lasts well beyond the sale.

Specifications