The THÖRESS EHT Integrated Amplifier is a revolutionary component that redefines the relationship between vacuum tubes and solid-state technology. "EHT" stands for EINTAKT-HYBRID-TRIODE (Single-Ended Hybrid Triode), a unique topology developed by Reinhard Thöress to bridge the sonic gap between the emotional purity of single-ended triodes and the driving capability of modern transistors. Operating in pure Single-Ended Class-A mode, this amplifier utilizes vacuum tubes for voltage gain and a unity-gain MOSFET stage for current buffering. The result is a 20-watt-per-channel amplifier that drives difficult speaker loads with authority while retaining the holographic soundstage, texture, and flow of a purist tube amp—all without the need for expensive, exotic power tubes or output transformers. What's New in MKIII The MKIII introduces a redesigned driver stage built around NOS Philips SQ E81L tubes, a special quality variant with a 10,000-hour lifespan. These gold pin tubes replace the previous 6J5GT/12J5GT/7A4 driver tubes, offering exceptional linearity that further refines the amplifier's sonic signature while ensuring long-term reliability. Key Features: EHT Topology: A unique Single-Ended Hybrid Triode circuit combining an E81L NOS Philips SQ vacuum tube driver stage with a high-current MOSFET output buffer. Class-A Operation: Runs in pure Single-Ended Class-A mode with high idle current for zero switching distortion and ultimate linearity. Tube Driver Stage: Utilizes NOS Philips SQ E81L tubes with 10,000-hour lifespan. The E81L's exceptional linearity determines the amplifier's entire sonic signature. Zero Global Feedback: Designed without any global negative feedback to preserve the natural dynamic structure and phase integrity of the music. High Damping Factor: The MOSFET buffer ensures very low output resistance, providing excellent control over loudspeakers with low efficiency or critical impedance curves. Remote Volume Control: Features a high-grade, motor-driven ALPS dual-potentiometer for precise channel balance (within 0.3dB) and convenient remote operation. Bass Boost Presets: The MKIII features two selectable bass boost curves (B1/B2) to subtly enhance low-frequency response for smaller speakers or specific room acoustics. In-House Transformers: Equipped with ultra-low noise, dual-coil C-Core mains transformers produced in-house by THÖRESS for exceptional power stability. The EHT Concept The philosophy behind the EHT Integrated is to allow the vacuum tube to do what it does best—amplify voltage—while relieving it of the heavy lifting of driving the speaker. In this design, the voltage gain is handled entirely by an E81L driver stage. This signal is then handed off to a unity-gain MOSFET output stage. Because the MOSFETs provide only current amplification without adding voltage gain, the sonic signature remains dominated by the E81L triode. This topology eliminates the need for an output transformer, reducing distortion and allowing for a much lower driver voltage swing compared to all-tube designs. Power with Finesse While 20 watts might seem modest on paper, the EHT Integrated delivers current with a grip that belies its rating. Thanks to its high damping factor, it can drive loudspeakers that would typically struggle with traditional low-power SET amps. The elimination of the output transformer removes a significant bottleneck in signal purity, resulting in a sound that is fast, transparent, and incredibly detailed, yet undeniably "tubey" in its harmonic richness. Smart Flexibility The MKIII features a practical 3-position toggle switch for Bass Boost. Unlike standard tone controls that can muddy the sound, these presets (Style 1 and Style 2) work by interposing just a single capacitor into the circuit. This allows you to restore body to lean recordings or flesh out the bottom end of compact speakers without compromising midrange transparency. Uncompromising Build Handmade in Aachen, Germany, the EHT Integrated is built to last a lifetime. The chassis is non-magnetic aluminum with a powder-coated finish and anodized printing. Internally, the construction relies on meticulous point-to-point wiring for the tube sections and high-grade PCB implementation where appropriate for stability. The mains transformer is mechanically isolated to prevent vibration, ensuring a noise floor that is pitch black. 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 Topology Single-Ended Hybrid Triode (EHT), Zero Feedback Operation Class Pure Class A (High Idle Current) Power Output 2 x 20 Watts (into 6 Ohms) Tube Complement 2 x E81L NOS Philips SQ (Driver Stage) Inputs 4 x Line Level RCA (Equal Gain) Bass Boost 3-Position Switch (Neutral, Boost 1, Boost 2) Volume Control Remote Controlled Motorized ALPS Potentiometer Mains Transformer In-house Hand-wound Dual-Coil C-Core Dimensions (W x D x H) 434 x 450 x 184 mm (includes feet and binding posts) Weight 18 kg (Shipping Weight) Origin Handmade in Aachen, Germany
