Jim Austin of Stereophile once played a deep bass test tone through a Devialet Expert 140 Pro and switched on a feature called SAM. Windows rattled at the far end of his room, about 40 feet from the speakers, something he had never experienced there before. SAM, for Speaker Active Matching, is software. Devialet measures a speaker's woofers in its lab and adds the speaker to its database, and SAM then reshapes the bass signal in real time so that, Devialet says, the sound follows the recording exactly. The amplifier underneath is just as unusual. A small, very clean amplifier sets the shape of the signal, while efficient helper stages beside it supply the current the speaker draws, which is how the whole thing fits in such a slim case. Austin heard the Expert 140 Pro as "honest, evenhanded, liquid, open," and What Hi-Fi? called its presentation "impressively crisp." Devialet suits listeners who want clean, precise sound from very little furniture.

If you already own speakers, start with an Expert Pro amplifier. The number in each model name is its power per channel into 6 ohms, and the 140 drove Austin's Revel Salon2s "with apparent ease." Setup is done through Devialet's online Configurator, which saves your choices to an SD card for the back panel. That is where you pick your speaker model for SAM or turn the RCA inputs into a phono stage, and Austin notes that a dealer can do it for you. If you would rather have a complete system with no separate boxes, look at the Phantoms, which are wireless speakers. The decibel figure in each name is the maximum volume at one meter. The Phantom II uses one full-range driver, and the larger Phantom I adds a tweeter. Whichever you choose, give the side-firing woofers room. Paul Sechi of StereoNET kept his Phantom Ultimate 108dBs well clear of the side walls and the wall behind, and he never passed half volume in his room.

The name honors Guillaume Vialet, an 18th-century engineer who worked alongside the Enlightenment philosophers and contributed to their Encyclopédie. Pierre-Emmanuel Calmel came up with the hybrid amplifier idea in 2004, built a prototype in 2007, and founded Devialet in Paris that year with Quentin Sannié, Emmanuel Nardin and Mathias Moronvalle. Their first product, the D-Premier of 2010, could hang on a wall, and it added a DAC to the usual phono stage, preamp and power amp. John Atkinson's Stereophile review of it was, in Austin's words, "a rave." Arnis Balgalvis of Positive Feedback found a D-Premier in Canada before Devialet had American distribution and used it as his reference for ten years, and Devialet has since rebuilt original D-Premiers in Paris as Expert 250 Pros. The Phantom followed in 2014. Its two opposed woofers face out from the sides of a sealed enclosure, and on a deep bass note, Alan Sircom of Hi-Fi+ writes, the sides "expand and contract like a beating heart." Devialet credits the pulsating-sphere idea to the loudspeaker pioneer Harry Olson.