As a kid in Slovenia, Blaž Erzetič could not afford a hifi system, so he built one himself and listened to it almost every day for two decades. He still builds things by hand, and he calls his headphone amplifiers "practically small power amplifiers." Sandu Vitalie of Soundnews found that the little Bacillus II+ comfortably drove his power-hungry T+A Solitaire P planars and kept "outstanding dynamics" with most of his headphones. The headphones get the same care. The Phobos and Mania have octagonal cups carved by hand from aged linden wood, and the Thalia's frame is held together only by nuts and bolts so a failed part can be replaced. Its cups are symmetrical, so either one can go on the left ear. Erzetich suits listeners who want a big, open sound from something handmade and repairable.

The Thalia is the easiest way in. It's an open-back on-ear headphone that Mateusz Chmura of Ear Fidelity says will play from anything with a headphone socket, "whether you're plugging them into an Apple dongle or into a vintage Discman." Passion for Sound notes its warmer, richer tuning for portable use. The step up is the Mania, a semi-open over-ear, and Reviews By WaveTheory heard a smooth, slightly dark and "very non-fatiguing" sound. Above it are the planar flagships, the Phobos and the Charybdis. Vitalie drove the Charybdis from a Topping A90 Discrete without high gain, though he suggests a fully discrete class-A amplifier to get the most from it. Erzetich's own Perfidus is a class-A design, and WaveTheory found it a good partner for the Mania and for fussy headphones such as the original Focal Utopia and the Fostex TH900. It also smoothed the treble of his HiFiMan models.

Erzetič played guitar in garage bands from high school and later released four albums. He earned his living as a freelance designer, and in February 2012 he expanded into building electronics under his own name. The first product was the Bacillus, which Ward De Wit of Best of High-End describes as an attempt at the smallest possible portable amplifier, and Ear Fidelity noted that it was still being sold. In March 2013 Wojciech Pacuła of Poland's High Fidelity reviewed the Perfidus and called his article the brand's international debut. The wooden parts are made in a workshop in the woods of Trnovo, and the electronics are assembled and tested in a second shop nearby. Peter Pialisu reviewed the planar Phobos for Headphone.Guru in 2019 and was reminded of Sennheiser's HD800S. The Charybdis followed with what Vitalie calls the biggest headphone drivers in existence. Paweł Szachno, founder of Ear Fidelity, met Erzetič at High End Munich in 2023 and later called the Charybdis "the best staging over-ear headphone I've ever heard."