The NuPrime STA-100 is shaking up the high-fidelity amplification scene by packing 100 watts per channel into a chassis weighing just 1.8 kilograms. This Class D stereo amplifier doesn’t just miniaturize: it introduces an adaptive switching power supply that dynamically adjusts its voltage according to the music’s instantaneous demands. Designed for audiophiles seeking both performance and discretion, the STA-100 requires an external preamplifier and is aimed at those who prioritize sound quality in a compact format.
The core innovation of the STA-100 lies in its “Adaptive Voltage Switching Power Supply,” a world first according to NuPrime. Unlike traditional power supplies that deliver a fixed voltage, this one continuously analyzes the incoming music signal and modulates its output voltage accordingly. This approach works much like a car’s turbocharger: at idle, the amplifier consumes little power and remains silent, but as soon as a demanding musical passage arrives, the power supply instantly ramps up.
The system operates at a switching frequency of 550 to 600 kHz, well above the audible spectrum, eliminating any perceptible lag. This speed enables exceptional musical responsiveness, with the amplifier “literally leaping” into dynamic passages before dropping back to complete silence. The audible result is more detail at low levels and explosive power in the fortes.
The STA-100 features a three-position gain switch (15x, 20x, 30x) located on the rear panel. This function allows precise adaptation of the amplifier to the characteristics of the source and speakers used. A 15x gain is suitable for powerful sources and sensitive speakers, while the 30x setting optimizes systems with weak signals or more demanding speakers.
Connectivity is kept to the essentials: a single unbalanced stereo RCA input for the audio signal, complemented by input and output Trigger connections for automatic cascading power-on with other devices. A USB 5V output delivers up to 1.6A to power lightweight accessories. This streamlined connectivity reflects the design philosophy: prioritize the quality of the audio path rather than multiplying options.
Despite its compact dimensions (151 x 136 x 51 mm), the STA-100 incorporates sophisticated protection circuits. These systems continuously monitor operating conditions: short circuits, overload, overheating, and undervoltage automatically trigger protections without damaging the amplifier. The high-speed gate driver error correction keeps distortion below 0.005%.
The graphite-finished chassis adopts a discreet profile that blends naturally into modern setups. Its identical dimensions to the NuPrime WR-2 network player allow for elegant stacking to create a complete system. The lightweight design makes installation easy while showcasing the efficiency of modern Class D architecture.
The STA-100 is primarily intended for bi-amplified systems requiring a dedicated power amplifier. It excels with standalone preamplifiers, home theater processors with preamp outputs, or digital sources with built-in volume control such as certain DACs or network players.
The amplifier is particularly well-suited to high-end bookshelf speakers and floorstanders with medium sensitivity. Its ability to deliver 150W into 4Ω allows it to drive demanding loads with ease. Listeners who prefer moderate volume will appreciate its ability to reveal musical details even at low power, while dynamic enthusiasts will benefit from its instant power reserves.
The STA-100 is a pure power amplifier, lacking volume control and source selection. It directly amplifies the signal it receives, requiring upstream equipment capable of managing level and switching. This separation of functions optimizes sound quality by avoiding interference between processing and amplification circuits.
The power supply modulates its voltage according to the music’s instantaneous needs. During quiet passages, it operates at a low level, reducing noise and revealing micro-details. As soon as a dynamic transient occurs, it instantly increases voltage, delivering the necessary power without limitation. This adaptability eliminates the dynamic compression typical of fixed power supplies.
The gain switch only adjusts the amplification factor without altering the sound signature. It optimizes the match between the source and speakers, allowing you to use the system’s optimal volume range. An incorrect setting can result in too low a level (loss of dynamics) or too high (premature preamplifier saturation).
The Trigger enables automatic cascading power-on. Connect the Trigger output of your source (player, preamplifier) to the Trigger input of the STA-100. The amplifier will automatically power on with the source and can in turn control other equipment via its Trigger output. This function avoids multiple manual operations and preserves component lifespan.
Vincent
Excellent little amp. The only downside is a slight hiss in the speakers.
Comment from July 26, 2025 — Experience from September 22, 2024
Fabrice
Very good power amplifier to drive my surround speakers.
Comment from April 24, 2025 — Experience from March 22, 2025
Christophe
Magnificent sound. Dynamic. Extremely simple. Minimal footprint. It is paired with a WiiM Ultra and Elipson speakers.
Comment from November 15, 2024 — Experience from November 04, 2024
