Solid State Power Amp Reviews

A mono pair of CH Precision M10s ($210,000/pair as reviewed) declares its presence in capital letters. Each channel consists of two large units, each almost 2' high, linked by a total of four umbilical cords. While the "lighter" amplifier unit weighs almost 117lb, the toroidal transformer–based power supply unit tops out at nearly 172lb. That's a lot of metal.

The first thing I noticed about the LAiV Audio GaNM monoblock amplifier is its unusual shape and size; it occupies space differently than the other, more basic amplifiers on my rack. The GaNMs sat there giving off a megalithic vibe.

Frederich Nietzsche distinguished between two approaches to culture: The Apollonian, which is characterized by order and rationality, and Dionysian, which is about chaos, intoxication, and vitality. Apollo was the god of Music, Art, Light, and Knowledge, and to Nietzsche, the Apollonian impulse was the main source of beauty.

A century ago, pioneering psychiatrist Carl Jung had a wild encounter with the power of sound. "In a village on the way from Lake Albert to Rejaf in the Sudan we had a very exciting experience," Jung wrote in his book Memories, Dreams, Reflections. He goes on to describe his participation in a tribal drum and dance ritual. "Night had fallen ... when we heard drums and horn blasts. Soon some sixty men appeared, martially equipped with flashing lances, clubs, and swords."

Launched in 1967, Quad's highly original, elegantly styled 33 preamplifier and 303 power amplifier were Quad's first all–solid state designs and among the first solid state separates. The 303 may have been one of the first "vertical" amplifiers. Together with the 405 stereo amplifier, which came out in 1975, and the FM2 and FM3 tuners, these products proved to be enduring, widely feted successes from their launch until they were discontinued, the 33 in 1982, the 303 in 1985. Meanwhile, they enjoyed massive production runs, were marketed worldwide, and were much admired for their modern industrial design. It's said that Quad sold 120,000 33 preamps and 100,000 303 amplifiers. Across two versions, the 405 sold even more.

Quad introduced new versions of the 33 and 303 (each component $1599) in 2024, apparently moved to do so by the continuing hot market for originals.

For several decades—from well before I toured the Boulder factory in 2016—I've wanted to get a handle on the best sound the now–41-year-old company can offer. Multiple listening sessions at shows had more than hinted at excellence. But neither my time in Boulder's large, dedicated music room, which was intentionally dry, nor exposure at various hi-fi shows left me convinced that I'd heard Boulder's full potential.

My first opportunity for an in-home audition came in 2021, when I reviewed the 866 stereo integrated amplifier ($17,500 with DAC, $16,000 without). But that entry-level (by Boulder standards) product, which Senior Engineer Jameson Ludlam said was released to build brand awareness and expand the company's reach by offering "a more accessible product that provides the features we think many people are looking for with the performance they have come to expect from Boulder," only provided a peek at the excellence I expected Boulder to achieve.

So when a last-minute review cancellation opened space to review the just-released Boulder 1151 mono power amplifier ($47,000/pair), I thought, "At last!"

Back in 2016, I documented the rise of class-D amps using the early TriPath technology. Used in the Bel Canto eVo 200.2, TriPath cracked open the door to the High End but was never admitted due to a dim and opaque treble. The second wave was based on B&O's ICEpower technology, again via a Bel Canto amplifier, the Ref1000M monoblock. ICEpower had more credibility and was accepted by many but, often, only with, ahem, due consideration for size and efficiency. There was an explosion of new class-D amps in 2016 when Stereophile featured glowing reviews of Bel Canto's e.One Ref600M monoblock, Theta's Prometheus monoblock, and NAD's Masters Series M22 stereo amp, all based on Bruno Putzeys's Hypex NCore technology modules. Finally, it seemed that class-D was "in the room," though, even to this day, there remain critics and quibblers who continue to deny them as true high-fidelity products.

Well, time does not stand still and neither did Bruno Putzeys. He, along with Lars Risbo and Peter Lyngdorf, had founded Purifi in 2015, and in 2019 he unveiled the Purifi Eigentakt power amplifier modules.