Grimm Audio PA1 Mono-Block Power Amplifier

The Grimm Audio PA1 is a Class AB mono-block power amplifier, and the first amplifier Grimm Audio has built in its thirty-year history. Each PA1 drives a single channel with more than 150 watts into 8 ohms, using a fully balanced circuit of 96 fast output transistors and a linear power supply. It was engineered as the power partner for the MU2, and shares that streamer's compact chassis by industrial designer Michiel Uylings.

Key Features of the Grimm Audio PA1

• Class AB mono-block design, one chassis per channel
• More than 150 watts into 8 ohms
• 96 fast power transistors on an aluminum circuit board, the "Pierick Amp" output stage
• Fully balanced signal path with no series coupling capacitors
• Linear power supply with an Amplimo toroidal transformer and 90,000 µF of reservoir capacitance
• Selectable gain of 26 dB or 18 dB to match low- and high-gain preamplifiers
• Balanced XLR and single-ended RCA inputs
• Automatic line-voltage switching and auto on/off standby
• Five-year limited warranty

Grimm Audio's First Power Amplifier

Grimm Audio built its name on digital and on decades of work in professional mastering: the MU1 and MU2 music players, the CC1 and CC2 master clocks. The PA1 began because the company struggled to find an amplifier that did justice to the MU2 in demonstrations. Prototypes appeared at Munich High End in 2023, and several years of refinement followed. The amplifier is named the Pierick Amp, in honor of engineer Henk ten Pierick, whose 1985 circuit concept forms its foundation. As Grimm Audio creative director Eelco Grimm puts it, "We have developed a solid-state amplifier capable of achieving an extraordinary combination of transparency, control, and musical naturalness."

The Pierick Amp Output Stage

At the heart of the PA1 are 96 small, fast power transistors mounted on a modern aluminum printed circuit board. The tight thermal coupling that aluminum provides holds the output stage at a precisely defined operating point. In Grimm's words, this gives "an extremely well defined power output stage setting point, through which the output stage impedance remains constant over the full cross-over region, resulting in the lowest possible distortion of dynamic signals." It is a Class AB design that behaves, through the critical crossover region, far more like the best of Class A.

A Linear Power Supply

The PA1 uses a traditional linear supply rather than a switch-mode design. A large Amplimo toroidal transformer was chosen for its minimal capacitive coupling to the mains, feeding 90,000 µF of reservoir capacitance for abundant current on demand. Separate local stabilization keeps the driver and feedback circuits working independently of the current the loudspeaker draws, so dynamics stay clean under load.

A Direct, Balanced Signal Path

The input path carries no series coupling capacitors, and protection circuitry keeps relay contacts out of the speaker signal path. Dedicated feedforward correction reduces phase-modulation distortion, the subtle time smearing that occurs when signal amplitude changes, and a second-order feedback loop lowers remaining distortion without reintroducing it. The damping factor exceeds 800, for tight control of the loudspeaker.

More from Grimm Audio

The PA1 is built to partner the Grimm Audio MU2, which combines a music streamer, DAC, and reference analog preamplifier in one chassis, with a single MU2 feeding a pair of PA1 monoblocks directly. Add the PW1 Phono Preamplifier for vinyl, or explore the LS1c active loudspeaker system.

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 exceptional service and relentless passion for hifi. 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.

Grimm Audio PA1 Specifications

Full measured specifications and pricing will be confirmed at launch.