Erzetich Bacillus II Desktop Headphone Amplifier Review – Backbone Of Ages
Erzetich Bacillus II is a $934 USD / 799 Euro Headphone Amplifier, the Entry-Level model from Erzetich, and it is a handcrafted amplifier, with a Class AB design. Today we review the Erzetich Bacillus 2 and also compare it with other Headphone Amplifiers including Singxer SA-1 V2 (599 USD), Aune S17 Pro Evo (799 USD), and Sparkos Gemini (995 USD).
Introduction
Erzetich is a popular company, best known for their handcrafted audio equipment, vintage – rustic design, and solid products, with outstanding quality and a specific warm, usually smooth house signature. Most Erzetich products are boutique or made to order, and they can be purchased from the official website, so it is best to check with them what the current estimated shipping time is for each product.
As an Amazon Influencer, I earn from qualifying purchases, and using the purchase links in my reviews helps me maintain this website and Youtube Channel. Audiophile-Heaven has no Ads and our Youtube Channel has no midroll ads, and our work is supported by Affiliate Links and Donations. Huge thanks to Erzetich for providing the sample for this review, in exchange for my honest opinion.
Product Link
Amazon – https://amzn.to/4nr8MoU
Aliexpress – https://s.click.aliexpress.com/e/_oFGwL8J
Build Quality – Design
Erzetich Bacillus II is a solid headphone amplifier with a rather mini size, but unusual shape and design. It is designed as an upgrade from the Bacillus Tilia headphone amplifier, but with improved electronics and refined design. It is designed to complement the Scylla and Deimos flagship models, creating a cohesive lineup of products for Erzetich.
Technically, Erzetich Bacillus II is a Class AB Headphone amplifier with a metallic chassis and wooden sides. It uses a Blue Velvet Alps potentiometer, and it adapts to headphone impedance. Internal wires are made of silver plated copper, using high-quality cabling inside of the amplifier, and it uses Obbligato gold premium quality pulse input capacitors.
Erzetich offers a 5-Year limited warranty, and Bacillus II is made in the EU, with a fully serviceable design, and a recommended time of 12 hours of burn-in. The recommended impedance for headphones to be powered by the Bacillus is between 8 and 600 OHMs, and it has a rated output power of 157mW (no rating for the impedance at which it can deliver this power).
With a rather low power consumption of just 3W, Bacillus II works with both USA and EU voltage ranges, 230V or 115V, and it has a weight of 1130grams. It has a single 6.35mm single ended jack headphone output, and has a frequency response between 2 Hz and 800 kHz with a deviation of -1dB.
Subjective Usage
As Erzetich Bacillus 2 is a Headphone Amplifier, it only has this function, so you basically have an RCA input, headphone output, and a power input. There is a power button at the back, and this is absolutely everything, besides turning the volume wheel and turning it on and off, there’s no other function.
There is no delay added by using the Bacillus 2, it has no audible background noise, it works as it should, and it works very well even with DACs that output a volume a bit louder than it expects, including setting all DACs I have at maximum volume. Although the sides have a glass finish it is not very fingerprint prone, and as you don’t need to touch it, you’re not likely to see fingerprints often and it will just work and look like a blend of vintage, cottagecore and modern on your desk.
I believe that Erzetich Bacillus 2 has only one disadvantage, and that’s that the power button is at the back. This being said, because the unit itself is so small, it is easy to reach around and turn it on and off. Happily, the unit does not have any other issue, heat is managed nicely, and it is very stable on my desk.
Sound Quality
Pairings – The main DAC I have used to power the Bacillus II is FiiO K17, and I have paired it with a selection of IEMs and Headphones including KBEar Cepheus, Crosszone CZ-10 Enhanced, NFAudio NE4, NfAudio NA2+, Rose Technics QT-X, Palma DHS-1, and RAPTGO LEAF D01, Moritz Dragon, Soundz Flame, HIFIMAN Arya Unveiled. It struggles a bit with HIFIMAN Susvara Unveiled but has an excellent match and pairing with Erzetich Thalia and Erzetich Mania V2024.
Overall Signature – Although Bacillus 2 has a short description online, it has a really powerful sound, tons of driving power even for super hard to drive headphones like HIFIMAN Isvarna, HIFIMAN HE1000 Unveiled, Susvara Unveiled and it can actually drive the original Susvara with a satisfying, powerful bassy sound. I am finding the Bacillus 2 to be so pleasing that I am using it quite a lot despite it offering just the headphone amp function with no PRE or other functions.
Bacillus 2 is great for all music styles, and if you want a darker, more powerful sound, it is versatile and clean, has an exceptionally controlled THD, and also excellent loudness saturation gradient control at all volume levels. It renders details and micro dynamics better than most DAC AMP combos, for example it is far above FiiO K17, for driving headphones, even when K17 is the DAC feeding it. This being said, as the main connection is RCA, if you’re using basic cables, you may hear the noise floor typically associated with an RCA single ended connection.
Bass – Bacillus 2 has a deep, powerful bass. It is evidently the central point of its sound, has an ultra deep delivery that creates punch, depth, and separation between instruments giving Bacillus 2 an exceptionally controlled and dynamic sound. B2 is also exceptionally good at controlling headphones, even those that usually show some increase in THD with bassy tracks, or at very high volumes, stay super controlled, deep and clear clean with Bacillus 2. I am talking about it being half the size of Aune S17 PRO Evo but far more maximum bass delivery with a lower distortion even with hard to drive headphones like HIFIMAN Susvara and Susvara Unveiled. Somehow, Bacillus 2 can put more backbone and power, more raw bass punch and depth than most amplifiers on the market, and even comparing it to others, it still delivers such an impressive low-end performance that if you felt your headphones did struggle, B2 could be the way to power them.
Midrange – Bacillus 2 renders a smooth, relaxed midrange that takes away some of the aggro force in voices, it creates a really enjoyable, lean, but fun experience. Resolution is exceptional, it renders far more details and separates instruments from each other, and creates a really layered experience, ignoring the bulky and compressed feeling usually heard in rock, metal and commercial, modern music. B2 is quite awesome at generally rendering each song deep, and it has a slight tonal preference towards the lower midrange, giving music presence and strength more in the lower midrange than in the upper midrange, resulting in more depth, more seriousness for male voices than for female voices.
Treble – Erzetich gave B2 a smoother, more relaxed treble, with a softer edge than the vast majority of amplifiers. While this sounds similar to most headphone amplifiers in the same range, there are some key differences, including the richer texture of the B2 despite the smoother texture and more relaxed presentation. B2 doesn’t cancel the treble, it takes away the aggro edge and pulls on the presence a bit to make way for the deeper bass, resulting in the darker overall tonality of the whole amplifier. Especially with bright and sharp sounding headphones, this results in a really open and clean signature.
Dynamic Range and Textures – Bacillus 2 is the type of amplifier that emphasizes and expands on the dynamics of a headphone, it gives all headphones a wider dynamic range, increases the micro dynamics and differences between instruments. Textures are organic – natural – rich, it renders a lot of textures but in an organic fashion, allowing music to stay clean and controlled, but detailed and rich without being harsh or fatiguing. The texture is quite natural, but the dynamic range it has is uniquely wide, quite a few levels above the direct competition.
Loudness Saturation Gradient – Bacillus 2 is fairly consistent relative to volume, it sounds excellent and really amazing at lower volumes, but it holds a similar level of control even when it is playing at louder volumes. It is able to have the same control at all volume levels, overall the signature is magical.
Soundstage – Erzetich gave Bacillus 2 a deep, layered soundstage. It enhances the separation you hear between distant and close sounding instruments, gives all instruments a defined bound, and it projects those laterally wide, but within a defined bound too. Overall, it is more focused on the imaging, layering and instrument separation than it is on pure width. This being said, B2 creates one of the deepest images presented by a headphone amplifier, much deeper than S17 Pro Evo and similar to the depth of HIFIMAN Prelude offers.
Comparisons
Erzetich Bacillus II vs Singxer SA-1 V2 (934 USD vs 599 USD) – Singxer designed the SA-1 V2 with a balanced design in mind, it has XLR, 4.4mm balanced outputs alongside the 6.3mm headphone output that can also be found on the Bacillus 2. Furthermore, SA-1 V2 can be used as a Preamplifier, it has RCA inputs, RCA outputs, XLR inputs and XLR outputs, with a fuse protecting everything, having a more versatile usage from a design standpoint. It also has more cooling and the design has multiple switches on the underside, with the power button being set at the front of the amplifier. This being said, you purchase a headphone amplifier for the sound and sonically Bacillus 2 sounds deeper, has more bass strength, a higher driving power, better punch and kick. Bacillus 2 is more engaging and has a more powerful sound, more color in the midrange, and Singxer SA-1 V2 is more relaxed, smoother, and has a more linear sound compared to bacillus 2. Sa-1 V2 has a lower noise for IEMS, but Bacillus 2 has a higher driving power and lower distortion at all volumes with hard to drive headphones.
Erzetich Bacillus II vs Aune S17 PRO Evo (934 USD vs 799 USD) – aune designed a really versatile headphone amplifier and S17 PRO Evo has XLR, 6.35mm and 4.4mm headphone outputs, a display, and it has RCA inputs, RCA outputs, XLR inputs, XLR outputs, and the option to turn it on and off frontally. From a design standpoint, S17 PRO Evo can work as a preamplifier, headphone amplifier, is balanced, and it solved the heat issues that the original S17 PRO used to have, all of which are very pleasing upgrades for the AMP. Sonically, S17 PRO Evo has less control at high volumes, but better control and a lower distortion when driving sensitive IEMs. Bacillus 2 is quite clearly designed to drive hard to drive headphones and will sound deeper, more beefy, with a deeper bass, while S17 PRO Evo sounds less aggressive, but also a bit more vague, less precise and less refined. Bacillus 2 wins in resolution, soundstage depth and width, instrument separation and overall maturity, texture of the sound. Although it costs more and has a less versatile function, Bacillus 2 is more tuned for a deep, slightly dark, but powerful and bassy sound.
Erzetich Bacillus II vs Sparkos Gemini (934 USD vs 995 USD) – Not only is Gemini an excellent Tube PRE / SS Power Amplifier, but it is actually single ended only, just like Bacillus 2. Gemini has only an RCA input, RCA output, and cattle plug power input, but with both the power button and the gain button at the front. With Gemini it does have a PRE function, and you can open it up to dial in more tube sound, and to fine tune it, and it uses the mighty Sparkos OP-AMPs. This being said, sonically, Gemini has a bit more distortion, the THD type, and it has a more open sound, brighter and more brilliant, while Bacillus 2 is more beefy, has a stronger sub-bass, much stronger bass, smoother treble, and a more personal, smoother voicing. Bacillus 2 makes music less aggressive, has a stronger instrument separation, and better depth. Gemini sounds vocal, forward and happy, Bacillus 2 sounds serious, refined, deep and a bit dark, thanks to the lower power in the treble and higher bass depth and impact.
Value and Conclusion
Erzetich Bacillus costs a bit more than the average market price of headphone amplifiers with a similar power delivery, but it has a unique rustic design, has a wooden frame and metallic chassis, it is impressive in the sound delivery. It has a good value for a handmade product made in the EU, but it has a bit of that boutique factor you need to consider.
At the end of the day, if you’re looking for a fairly beefy headphone amplifier from Erzetich, with a beautiful sonic performance, smooth, silky sound, high impact and a strong bass, Erzetich Bacillus II is an excellent option for a more rustic looking AMP with a rustic, organic and romantic sound.
PROs
- Strong build quality, literally feels like a tank
- Made in EU, with most components hand made and hand assembled
- Large volume wheel with a nice damping
- Clean sound with very low distortion, high-end sound
- Bloomy, silky sound, excellent at both high and low volumes
- Revealing and engaging
Cons
- Single ended design with only RCA Inputs and a 6.35mm output
- No Preamp function
- Boutique handmade pricing
--- Please remember to stay safe, and always have fun while listening to music!---
- If you have a dime to spare, please donate, and help us! It would make the day brighter for me and my wife-
Full Playlist used for this review
We listened to more songs than those named in this playlist, but those are excellent for identifying a sonic signature. I recommend trying most of the songs from this playlist, especially if you’re searching for new music! The playlists are different for Spotify, Tidal and Youtube, and based on the songs I enjoy and are available on each!
https://www.youtube.com/playlist?list=PL_cjBXGmwSHSdGcwuc_bKbBDGHL4QvYBu
https://open.spotify.com/playlist/5J3oloz8Riy9LxEGenOjQ0?si=979ba4f082414be7
https://tidal.com/browse/playlist/330fd544-8e5b-4839-bd35-676b2edbb3d5
--- Contact Us ---
