Perfidus headphone amplifier From Erzetich

6th April 2018

Arriving in a slimline chassis, Paul Rigby reviews Erzetich’s solid state Perfidus headphone amplifier 

There are users out there who will buy a separate headphone amplifier as an upgrade to a built in model found within an integrated amplifier, for example. The reason? Separating devices dedicated to a single task is always beneficial because it lowers noise from cross-contamination and also provides more chassis room to integrate higher quality components. Of course, many hi-fi fans already know this and will buy a separate headphone amp from the off.

Perfidus headphone amplifier Form Erzitech 

In amongst the wholly admirable sound quality concerns, though are more obviously physical practicalities. That is, a separate headphone amplifier is another box to stuff onto a shelving unit. Finding space for an additional chassis can be an issue and so, even before we get to the specific sound issues of the Perfidus, Erzetich will find favour amongst many potential customers because its aluminium chassis is of a slimline nature. Spanning just 110 x 64 x 285mm and weighing in at 1.48kg, this is a wholly unobtrusive design that you can slot into a relatively small shelving slot. 

Perfidus headphone amplifier Form Erzitech 

As owner/designer of the Slovenian company, Blaž Erzetič described, the design did undergo a measure of evolutionary change, “We called this unit In-Cubus in the first stages. It was meant to be in a cube-like chassis: power supply at the top and amplifier circuit at the bottom. But it didn’t work out as expected. No matter what we tried with the electro-magnetic isolation, the interference from the power supply was too strong. So on to Plan B: put it in the Bacillus’ chassis and make it slightly longer.”

Perfidus headphone amplifier Form Erzitech 

Standing on rubber feet, the Class A unit features a 7mm aluminium front panel (2mm at the back) featuring a solid aluminium volume knob, headphone socket and an LED light. Around the back are a pair of RCA connectors and the power switch. Build quality is reasonable but messy with screws sticking out of the chassis sides as almost an after-thought. This is not a £200 lucky bag of random parts stuck together in haphazard fashion or even an agricultural, valve-based construction, I expected more for £1k’s worth of solid state. Lose the screw heads, please Blaz.

This unit has been around for a while now but this latest iteration features improved cabling, a different chassis, improved connectors, a stronger transformer and some additional improvements to the board inside.


I began with a vinyl reissue of Gary Numan’s Dance, over 2LPs and a single from that album, She’s Got Claws.

Perfidus headphone amplifier Form Erzitech 

Precision. That’s what I hear when running the Perfidus. Every element the soundstage, every instrument, every vocal inflection was infused with precision. 

The synth-based instruments benefited enormously from this sonic element because their sometimes breezy inflections were honed to a crisp state that brought out the detail in a sort of bas-relief making it easier on the ear to pick out even subtle modulations. This one element in itself enriched the music, adding complexity. 

Perfidus headphone amplifier Form Erzitech 

This meant that subtle and rather shy percussive synth sequences were more readily detectable, fattening the soundstage a touch. In terms of treble, as real drums are used on this track, the cymbal strikes were firm with a shine that illuminated. An effect that will be familiar to all solid state fans. 

Perfidus headphone amplifier Form Erzitech 

Valve fans might miss the air and space that infuses the soundstage but the Perfidus, while still retaining plenty of movement, replaced much of that with a finger-clicking focus, pushing the midrange detail close to the ear. You could hear this easily during the final bass guitar solo  – and what a solo it was! Footless and fretless – the notes were plucked, twanged even with a definite and defining exactitude. There was no messing around here. No possibility of interpretation. The story of the bass guitar solo is laid down ‘as is’. As is the Numan vocal which, despite his trademark lyrical slur, was distinct in its (relative) accuracy. 

Perfidus headphone amplifier Form Erzitech 

I moved to A Bucket of Tears from Peggy Lee from her album Extra Special! Again, this jazz vocal, fronting a full orchestra, was clean, clear and capable. Lee’s delivery was a vision of clarity as her emotive nuances were tracked easily and successfully by the Perfidus. Her performance was both smooth and fluent, the Perfidus giving Lee the impression that she was enjoying herself. You could almost imagine her swing her arms and hips as she was singing this uptempo ditty.

Perfidus headphone amplifier Form Erzitech 

The brass section of the backing orchestra was crisp and open without a grain of dust to spoil the clarity. The upright bass was easily tracked by the ear, no smearing or blooming here, while percussion from the bongos offered a neat performance that retained its own reverb tail.


Solid state fans will lap up the accuracy and the precision of the Perfidus’ performance. Both treble and midrange are scrupulous in their approach with a transparency that will delight many ears while the bass, while not particularly massy, is certainly punchy and full of effect-filled impact. 

Providing a big sound from such a small footprint, the Erzetich Perfidus allows music to flow with ease.


Price: £999

Tel: 01334 570 666 


GOOD: clean midrange response, shiny treble, accurate bass, precision 

BAD: chassis finish


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All vinyl was cleaned using an Audio Desk’s Ultrasonic Pro Vinyl Cleaner