The THÖRESS DFAmp (Dual Function Amplifier) is a purist vacuum tube component designed to serve two critical roles with equal mastery: acting as a reference-grade Line Control Preamplifier and a high-performance Headphone Amplifier. By utilizing a unique, minimalist Single-Ended Zero-Feedback circuit, the DFAmp delivers the same rich, textured, and dynamic performance whether driving a power amplifier or a pair of high-end headphones. Features ultra-low output impedance, it handles long cable runs and difficult headphone loads (down to 50 ohms) with ease. With its integrated "GT Selector" for on-the-fly gain and tone adjustment, the DFAmp offers a level of flexibility rarely seen in such a purist design, making it the perfect heart for a sophisticated analog or digital system. Key Features: Dual Functionality: Serves as both a reference Line Preamplifier (driving power amps) and a dedicated Headphone Amplifier (driving headphones via dual 6.35mm jacks). Minimalist Topology: Features a Single-Ended Zero-Feedback circuit using 12J5GT gain tubes and 12GN7 power pentodes (in triode mode) for ultimate linearity. GT Selector (Gain/Tone): A unique 6-position rotary switch allows users to select between different gain levels and subtle, passive tone presets (Bass/Treble boost) to match headphones or recordings. Versatile Inputs: Equipped with 6 line-level inputs grouped into High, Medium, and Low gain stages to perfectly match sources ranging from phono stages to high-output DACs. Triple Master Output: Features three parallel RCA main outputs, allowing for bi-amping or tri-amping configurations, or the easy addition of active subwoofers. Remote Volume Control: Includes a motor-driven ALPS dual-potentiometer for precise channel balance and convenient remote volume adjustment. One Circuit, Two Roles The magic of the DFAmp lies in its ability to perform two functions without compromise. The signal path consists of a 12J5GT triode gain stage followed by a unity-gain current buffer using a powerful 12GN7 pentode (wired in triode mode). This buffer provides high current and low output impedance, meaning the amplifier can drive the complex loads of dynamic headphones just as easily as it drives the input stage of a power amplifier. There is no separate "headphone circuit"—you are always listening to the full, main tube stage. The GT Selector: Intelligent Control Rethinking the concept of tone control, THÖRESS introduces the GT Selector (Gain & Tone). This 6-position dial allows you to switch between "Neutral" response and various subtle Bass or Treble boosts entangled with gain attenuation. Unlike clumsy traditional tone knobs that degrade the signal, these presets are realized by interposing just a single capacitor per channel. This feature is invaluable for correcting thin recordings or adding body to lean-sounding headphones. Optimized Gain Structure To maximize signal-to-noise ratio and volume pot usability, the DFAmp’s 6 inputs are divided into three gain groups. Inputs 1-3 offer High Gain (ideal for external phono stages or tuners), Inputs 4-5 offer Medium Gain (perfect for standard DACs/CD players), and Input 6 offers Low Gain (for high-output vintage digital sources). This ensures you always operate the volume control in its optimal range, regardless of the source. Hand-Built in Germany As with all THÖRESS components, the DFAmp is a labor of love. It is constructed entirely by hand in Aachen, Germany, using point-to-point air wiring. The proprietary mains transformer is wound in-house and mounted on isolation elements to eliminate mechanical vibration. The non-magnetic aluminum chassis features a retro-lab aesthetic with a powder-coated finish, ensuring the unit looks as distinctive as it sounds. 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 Triode (Zero Feedback) Tube Complement 2 x 12J5GT (Gain), 2 x 12GN7 (Buffer) Inputs 6 x Line Level RCA (grouped by gain) Input Gain Structure High (Inputs 1-3), Medium (Inputs 4-5), Low (Input 6) Outputs 3 x Master RCA (Parallel), 2 x Headphone (6.35mm Jack) Headphone Impedance Drives loads down to 50 Ohms Tone Control 6-Position GT Selector (Gain/Tone presets) Dimensions (W x D x H) 434 x 434 x 154 mm (H includes feet) Weight 11.7 kg (Shipping weight) Construction Hand-wired Point-to-Point, Non-magnetic Aluminum Case Origin Handmade in Aachen, Germany
