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Real Review - Erzetich Bacillus Headphone Amplifier

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A new RealReview from a new reviewer David Ayers.

The Erzetich Bacillus Headphone Amplifier.


Erzetich are a new name to me, I had to look them up on their website: http://www.erzetich-audio.com/ to see that they hail from Slovenia. There’s been a huge growth of excellent products coming from eastern Europe in the last two decades, including very familiar names such as Pro-ject and Kuzma. Interestingly the alternative headphone amp I had to hand during this review was the base model Pro-ject headbox, which I’ve been using for some years.

Currently Erzetich only list five products, four headphone amplifiers and a headphone stand. The Bacillus is their entry level model, currently available at £499.99 via Elite Audio: http://www.eliteaudiouk.com/

Now, I’ve been a headphone listener since I got into music (and hi-fi) 45 years ago, but my main focus has always been listening through speakers, and hence so has my main expenditure. Having said that, I still listen through cans a lot of the time, whether it’s at work (closed back) or at home when I don’t want to disturb the neighbours (open back). So saying, I was very interested to find out what one gets when moving up past the basic level of either an inbuilt headphone amp or a basic add-on such as the headbox. For this reason, although I had the choice of reviewing any of the four amps, I chose the Bacillus. This is a journey I have considered, and I’m sure many other have also.

Unboxing the Bacillus revealed a fairly small, but chunky box, with a similar footprint to the headbox, but around two and a half times taller. The Bacillus needs this extra space as it has an internal power supply, and not a wall wart.


Round the back there are two RCA inputs for left and right, a standard IEC mains connector, and an on/off switch. As the switch is round the back, one could assume that the unit is meant to be left powered up, but I found it only needed about 15 minutes powered up to come on song, so I opted to switch it off between sessions. No mention is made of this in the manual. A standard IEC lead was supplied in the box, and I used the unit with the supplied cable.

The Pro-ject Headbox that I have has a passthrough capability, in other words it has two pairs of RCA sockets to enable the amp to be placed directly in the line of a source component to the amp. The Bacillus doesn’t have this facility, so it will either have to be connected to a dedicated headphone source, or to the tape outputs of an amplifier. I initially connected it to the tape out of my Musical Fidelity M3i integrated amp, but subsequently I connected it directly to the outputs of my Pioneer N50a network player (more on that later). Other equipment I used was the line output of my Fiio X5ii portable player, functioning both as a DAC and as a stand-alone player. Headphones used were the B&O H6 closed back model and a pair of vintage Koss HV/1a open back cans, which I have owned from new.


So, what does one get when moving up the food chain from a basic head amp to something more capable? Clarity and control would be the best way to sum it up, in fact the same things you get when you upgrade an amp driving loudspeakers. Unfortunately this can also come at a cost, where the music is lost in the detail, a bit like focussing on the pixels in a picture rather than the picture itself. Was this the case with the Bacillus? Categorically no!

The first and most obvious impression I got when listening to the Bacillus was the extra weight to the bass, but not in a bloated way. In fact the level of control was very impressive. The H6 can be a little bass light, but driven by the Bacillus, this was much reduced albeit not entirely eliminated. The Koss cans on the other hand are blessed with a prodigious bass which can be a bit loose and uncontrolled. The Bacillus took these cans and told them in no uncertain terms what they should and should not be doing. The bass impact was hugely improved, with little or no overhang, cleaning up the mid and treble in the meantime and making them really sing. I’ve always felt the HV/1a is a very musical headphone, and the Bacillus took those qualities and cleaned them up without damaging any of the characteristics that have kept me coming back to them year after year.

I tried some modern highly compressed recordings, such as Black Holes and Revelation by Muse, and the Bacillus seemed to untangle as much as is possible out of this album, whilst making it plain that compression comes at the cost of bass depth and impact. Another recording that is normally tricky is the drum & bass influenced Earthling by David Bowie. This album can sound pretty relentless and to an extent this is intended, but without control the incessant thud thud thud of the percussion can be headache inducing. The Bacillus impressively sorted all the ducks in order, making the musical intent a lot clearer. I tried I’m Afraid of Americans on both sets of cans, and whilst the presentation was different, the overall effect of the Bacillus was maintained.

As I write this I am listening to Stevie Wonder’s Innervisions, and the rhythm and bounce of this most excellent album is a joy to hear. Stevie’s vocal inflections are coming through clearly and the whole tonal balance is excellent. When I had the amp connected to the tape outs of the M3i, I felt that there was a (very) slight bass lift, which is why I changed to a direct connection from the N50a to the Bacillus. That the amp can demonstrate this through cans is quite impressive.

The amp isn’t perfect of course and if I want to be picky then a couple of times when things really got going I felt it could be a bit like an overexcited teenager at a party, but this was slight. Also, whilst it was very good at making sense of dense musical passages, I have heard better through loudspeaker systems, and so I imagine it can be improved on by going for one of the amps higher up in Erzetich’s range. Interestingly Erzetich themselves characterise the amp as slightly bright, which was not my personal impression.

Manufacturer’s Specifications

Headphone impedance: 8-600 ohm

Output power: 181.5 mW (8 ohm)/161 mW (600 ohm)

Frequency response: 3 Hz-500 kHz, -1dB

THD (1 kHz): 0.0003 %

IMD: 0.025 %

Power consumption:> 3 W

SNR: >102 dB

Power supply input voltage: 230 V/50 Hz or 115 V/60 Hz

Dimensions (W x H x D): 110 mm x 64 mm x 180 mm

Weight: 850 g

Character: Slightly bright


Whilst this might be an entry level amp for specialists Erzetich, for most it is a step up from base level headphone amps or built in headphone outputs. As such, it is an obvious and worthwhile improvement and I’m sure that most people would be very happy moving to the Bacillus. For anyone looking to upgrade, I would recommend auditioning the Bacillus.

A REALREVIEW by David Ayers

For further information on this review or if you would like a REALREVIEW on any of your products please contact the content team on press@hifiwigwam.com

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