Headphones amplifiers — Erzetich Audio Bacillus II

The Bacillus II is the entry point of the headphone amplifier range from Erzetich Audio of Slovenia, listed by the maker at 799 EUR. It sits below the Bacillus II +, the Perfidus, the Deimos and the Scylla in the current catalogue, and no other model in that group is built around a compact single-ended layout with RCA input only. The company assembles it in the EU and gives it a 5-year limited warranty.

Key specs that matter

Rated output is 157 mW, and Erzetich states that the circuit adapts to headphone loads anywhere from 8 to 600 ohm. The published frequency response runs from 2 Hz to 800 kHz within 1 dB, a tighter tolerance than the 3 dB window used in many spec sheets. Connections are kept simple - one pair of RCA sockets at the back and a single 6.35 mm jack at the front, with no balanced socket on either side. Mains supply is 230 V at 50 Hz or 115 V at 60 Hz, depending on the version ordered, and consumption is only 3 W. The case measures 145 mm wide, 70 mm high and 180 mm deep, and the unit weighs 1130 g.

Engineering and use context

Circuit topology is class AB. The signal path uses Obbligato Gold pulse capacitors at the input, high-grade op-amps for gain, and silver-plated copper wire for the internal links. Level is set with a Blue Velvet potentiometer from Alps, turned through an oversized knob that dominates the front panel. The metal chassis has an angled top surface and wooden side cheeks, a styling cue the maker carries across its smaller amplifiers. Every unit runs through a 12-hour burn-in at the factory before shipping, and Erzetich describes the design as completely serviceable, so a failed part can be swapped instead of the unit being discarded. The small footprint and low power draw let it sit next to a computer or a compact source on a desk without needing a dedicated shelf or extra ventilation space.

Pairing

A line-level source with RCA outputs, such as a stand-alone DAC or a CD player, connects directly. Because only a single-ended jack is fitted, headphones terminated in 4-pin XLR or 4.4 mm plugs need a single-ended cable or adapter. The wide load range spans low-impedance planar designs and high-impedance dynamic types, and Erzetich lists its own portable-oriented and open headphones in the same catalogue for owners who want a single-brand chain.

Alternatives

At 999 EUR, the Erzetich Perfidus offers class A amplification for headphones one step above in price.