⌈ AURORASOUND is a Japanese company founded in 2010 by Mr. SHINOBU KARAKI. Brand’s lineup includes preamplifiers, phonostages and amplifiers, but also a headphone amp called HEADA, one that we received for this test. ⌋

ne of my favorite moments is when a new issue of the "Stereo Sound" magazine arrives from Japan. I grab it and sit comfortably on the couch or - if the weather allows - on the balcony and truly excited browse through it from cover to cover. It’s a thick volume of 500 pages, fortunately in the format similar to B5 - and it is probably one of the best audio magazines in the world. I can’t speak or read Japanese, which I truly regret. However, the "Stereo Sound" is largely a picture magazine, with excellent photos taken by magazine’s photographers, graphs, technical specifications, and so on. In my defense, the graphic form of the characters of the Japanese script - and these are: kanji, hiragana syllabary and katakana syllabary - justifies my linguistic ignorance.

The AURORASOUND company is one of those manufacturers that has caught my attention years ago, thanks to this Japanese magazine. These are high-class, but simple in appearance devices, stylized for the 1970s. due to the wooden housings similar to ones known from Marantz devices, and because of properly selected knobs, great workmanship and finish, and last but not least, betting on semiconductors.

In a mini-interview given to Marek Dyba for the review of the ViDA phono preamplifier, Mr. SHINOBU KARAKI, the founder and chief designer of the Aurorasound said:

The advantage of a transistor is in its physical characteristics. Frequency response, Total harmonic distortion, Signal-to-Noise ratio etc.…all of them are 10 times or more superior than tube devices.

A few simple words… SHINOBU KARAKI, „High Fidelity” № 190, 16th May 2020, accessed: 10.06.2020 | you can find the review HERE

Mr. Karaki-san started his adventure with audio with tubes, but his first product was the CEDA, a solid-state line preamplifier with a built-in DAC. Currently, the company's lineup also includes the PADA power amplifier, based on EL34 tubes, and the PADA-300B model with, obviously, 300B triodes, but even the latter features transistors in the input stage. The point is simply that wherever low noise and distortion are required, i.e. particularly for smaller signals, the company chooses to use semiconductors.

| HEADA

The Aurorasound uses capital letters in their products names. This procedure is often used by companies because it allows their names to be distinguished from others. In this case, though, the reason is different - names are actually abbreviations. And so, the VIDA is a Vinyl Disc Amplifier, and the HEADA - a Headphone Amplifier. In Polish, this type of entry is used for mixed letter-group abbreviations (such as 'PZMot' - Polish Motor Association). So if it were a Polish company, the correct name of the tested headphone amplifier could be: HeadA.

Anyway, we are talking about a high class headphone amplifier featuring a balanced output topology; the input section is unbalanced though - hence its full name: Balanced Drive Headphone Amplifier. It is not particularly big, but its proportions are very nice. Its appearance is defined by the front panel made of aluminum and the wood that covers the internal metal housing. It has a decorative purpose, but also affects the vibration damping, and thus the sound. The device features an integrated power supply, so one plugs a power cable directly into the inlet on its rear panel.

| A few simple words…

SHINOBU KARAKI 
Owner, designer

WOJCIECH PACUŁA: Could you tell us, what is the most difficult task when designing a headphone amplifier?
SHINOBU KARAKI: There are many kinds of headphones on the market, with different impedances and sensitivities. Recently 40-60 ohm impedance is quite popular, but there are also some professional cans with 600 ohm and vintage ones with 8 ohm..., and so on.  To ensure good sound with such a wide variety of headphones, a headphone amplifier needs to be able to drive them all properly, a good SNR and low THD are also important.

For power amplifiers for speakers, a high dumping factor is important, but for a headphone amp, a high dumping factor is not good. SNR and THD are the most important features for micro listening using headphones, but the amplifier also needs a large head room for big dynamic range. And to cover all those headphones, their users have to choose a different volume level, appropriate for their needs. So for a headphone amp any position of the volume knob and L/R balance have to offer the same sound quality. Long story short, a headphone amp needs particular attention and engineering know-how.

WP: HEADA features a balanced output but unbalanced input - why? (XLR input is there just for convenience?)
SK: HEADA’s input stage is unbalanced and the output is balanced - that’s correct. Because the idea, the sale point for HEADA, was to properly drive balanced headphones, not to be a fully balanced device. Fully balanced design is sometimes not that good because volume control parts needs 4 gang which results in a small error in low position.

WP: Is this a DC circuit or with capacitors in series?
 SK: Capacitor is inserted in initial stage of HEADA, because this can protect it against a DC leakage from signal source - from a player, D/A converter, etc. If there is no capacitor that can block DC leakage, headphones voice coil might be damaged. HEADA amplifier stage features no capacitor though, it is a real DC amp, and has DC leakage sensing and shutdown mechanism to protect headphones.

WP: What headphones do you use at your home, just for pleasure?
SK: I have Beyerdynamic T1, Shure SRH1840,  Sennheiser...etc.

WP: What kind of music do you listen to? Could you recommend one album for our readers?
SK: I like Jazz, Blues and some female vocal, sometime I listen classical music. color="#3857b0">SK

Features | On the front of the amplifier there is a nice aluminum knob that controls the volume. It is placed on the left side of the amplifier, so it is easier for left-handed people to operate (at least this once they have it easier :)). In the center there are three different headphone outputs. From the left, these are: the 6.3mm TRS (unbalanced output), 4-pin XLR (balanced) and two 3-pin XLR outputs forming a stereo pair (balanced output). The sockets are gold-plated and come from the Swiss company Neutrik.

All outputs are active simultaneously, so you can connect several pairs of headphones to the HEADA at the same time. I don't know why would you do it, but you can if you want to. The gain of the circuit can be adjusted to a specific headphone model. There are two levels to choose from: "low" and "high", but the manufacturer does not specify the actual values. In the real world, even with the switch in the "low" position, one can drive most models, even magnetostatic ones, such as the HiFiMAN HE-1000 v2.

The amplifier offers two independent line inputs, and one of them features both, RCA and XLR sockets. The block diagram provided by the manufacturer shows that the input stage and the attenuator are unbalanced, and the XLR input was added simply for convenience - the signal is taken from its positive pin, and the negative one is connected to the ground via a resistor. User selects between these two inputs with a toggle switch located on the front panel. The RCA sockets are of high quality, they are rhodium plated Furutech components.

It is a very nice, classically Japanese (just as products by Leben, Luxman and Accuphase), neat, functional device.

| HOW WE LISTENED TO IT

The HEADA amp offers three different outputs and two different inputs. The manufacturer recommends load in the range from 16 to 600 Ω, so it is very versatile. The output circuit is highly efficient as with 40 Ω cans it is able to provide up to 2 W, and with 600 Ω loading, 0.8 W. That's a lot. So we can experiment with any headphones - both with unbalanced and balanced cables.

For the test I used several quite different headphones:

• HiFiMAN HE-1000 v2 – planar/magnetic design, impedance: 35 Ω, sensitivity: 90 dB/V SPL; review HERE
• Sennheiser HD800 – dynamic design, impedance: 300 Ω, sensitivity (measured): 103.77 dB/V SPL,
• AKG K702 – dynamic design, impedance: 62 Ω, sensitivity (measured): 103.60 dB/V SPL; review HERE,
• Beyerdynamic DT-990 Pro (firsr version, 600 Ω) – dynamic design, impedance: 600 Ω, sensitivity (measured): 97.56 dB/V SPL; review HERE.

The HiFiMAN and Sennheiser headphones featured after market cables - the top model from Forza AudioWorks, the Noir Hybrid HPC model, and this Polish manufacturer prepared also adapters for them, which allowed me to test these headphones with all of the amplifier’s outputs.

The Aurorasound HEADA was compared to the Ayon Audio HA-3 and the Leben CS-300X (Limited Edition), and also to the output of the Mytek Brooklyn Bridge audio files player. The source of the signal was the aforementioned Mytek (files) and the Ayon audio CD-35 HF Edition SACD player (№ 1/50). The amplifier was powered using the Acrolink 8N-PC8100 PERFORMANTE NERO EDIZIONE № 1/15 cable (more HERE).

| SOUND

One thing is certain from the very beginning: HEADA offers an amazingly refined sound. In general terms, it resembles the one I remembered from the current outputs of the battery-powered Bakoon HPA-21 headphone amplifier. However, HEADA has no problems with driving any headphones, while the HPA-21 fared better with dynamic headphones with a higher than average impedance.

It also delivers an extremely open sound. On the one hand, it is delicate and pastel, and on the other, very resolving. The resolution in question manifests itself in a clear sound image, rich with tiny information, but without sharply cutting individual instruments out from the background. This is how its "pastel" sound, that I mentioned, manifests.

When I first listened to the newly released album Tsuyoshi Yamamoto Trio, with a concert recorded on November 16, 2019 in the Jazz Is club (Yokohama, Japan), I was struck by how much information can be conveyed, while not overwhelming or tiring listener with it. All you need to do is to show them in context, in perspective, not "by themselves".

This is important because HEADA is not an amplifier that would boost up the sound like tube devices do. For example, just like the Leben CS-600X or the Ayon Audio HA-3 do. So there is no "peak" in the lower midrange in its presentation, which, when applied, on the one hand helps to enlarge the volume of the sound and brings the foreground closer to the listener, and on the other hand it tames the "headphone" sound a bit, which is has no supported from room’s acoustics. And any room usually means boosting some bass frequencies up. However, this boost of the lower midrange is a modification of the sound, and one should be aware of it.

So the Japanese amplifier presents sound without coloration. It allows user to choose the final tonality of the presentation by matching appropriate headphones to it. But in this neutrality HEADA is not ruthless. It is, as I’ve said, a delicate sound, because the attack of the sound is spread over time, it is not a hard “wall”, but rather a silk wallpaper with a varying surface. And it doesn't matter what album we listen to. The better the recording, the more this multi-dimensionality of the attack phase is clear. But also on quite bright sounding discs, such as the Songs From The Big Chair by Tears For Fears, which contains quite high and "thin" sound, even on the excellent Platinum SHM-CD re-edition, this effect is perfectly audible.

So we already know that it is an open, neutral sound, but with a silky attack and a pastel tone. There is also a very good resolution. Exactly on the same day I received the HEADA for the test, from the Japanese CD Japan store, where I frequently purchase music, the new version of Frank Sinatra's album Nice'N'Easy, released on the 60th anniversary of its premiere, finally arrived. I compared it with other versions I have and this comparison with the Aurorasound amplifier was easy, simple, and results unambiguous, but also pleasant.

| Our albums

⸤ FRANK SINATRA: Nice’n’Easy | 60th Anniversary Edition
Capitol Records/Universal Music LLC (Japan) UICY-15883 (1960/2020)
Format: Compact Disc

Vertical - 60th anniversary version of the original release, on the left Mobile Fidelity version, on the right one from the Sinatra – The Capitol Years box
_____________

Sinatra's albums are reissued regularly, both on LPs and in digital form - on CDs, SACDs, and now also in audio files. However, these are not equivalent re-editions. They differ in terms of sound quality - understandably - but also in mixes (a large part of the original recordings are available in the form of three-track tapes), and even in the selection of "takes", i.e. successive versions of the same piece. It all depends on the person who works on the particular re-edition.

The latest re-edition of the Nice’n’Easy, which came out for the 60th anniversary of the original release, was prepared from the "master" tape by Larry Walsh, with the help of Leon Smith from NBC Universal Audio. I compared it with two previous, acclaimed digital reissues: the 1998 remaster of - the very same - Larry Walsh, which was released as a part of the Sinatra - The Capitol Years box, and the gold re-edition prepared by Mobile Fidelity from 2002, the master for which was prepared by Shawn R. Britton.

It's hard to believe, but the new version is the best I have - even better than the "golden" MoFi album. The sound here is dense, saturated and nice. The excellent instruments that sound thin and dry on the box release now sound much, much better. The MoFi version is equally saturated, but less - surprisingly! - resolving. The vocals still feature this weird monophonic reverb they were recorded with, but this version doesn't irritate. The more so that the orchestra here is fantastic - it is one of the best presentations of the orchestra’s accompanying Sinatra performances that I know, regardless of the format. This is a great re-edition of a very good album!

And now an interesting fact - in the anniversary version, the correct channel layout has been restored - strings are on the left and wind instruments are on the right, exactly as it happened during the recording session in the Room A at Capitol Studios, ran by Nelson Riddle (you can find the layout of the instruments HERE). In this way, the proper sound panorama was restored, although at the same time the idea (i.e. an error) of the original edition was changed. ♦

The tested amplifier is also great at presenting the low end of the range. So it impressively filled in the sound on the Aquavoice album Silence as well as beautifully presented the momentum of music from the Moonmadness by Camel. And it didn't matter which headphones I used to listen to it, because it always showed their better side and extended, very wide frequency response.

But it is also not a device that would guarantee something, which we know from tube amplifiers that show the sound right in front of us, close, in a dense way. "Density" is probably not the first word I would use in HEADA’s context. It would rather be: "transparency", "openness", etc. So if you are a fan of highly saturated sound, if you like a "sound massage", you should probably look for another amplifier, for example the Leben CS-600X .

HEADA has a different goal, as long as I read it correctly: it is about delivering a maximally stress-free, open sound, one that includes an incredibly wide panorama with great depth, not only in binaural, but also in classic recordings. You can listen with it to the music for a long time, without getting tired, but also without falling asleep. Because it offers an open, transparent, well-balanced sound.

Headphones | For a large part of my listening sessions I used the HiFiMAN magnetostatic headphones. They require a lot of current and decent control and that is what HEADA offered them. They are transparent and accurate, therefore they do not tolerate brightening and hardening of the attack, and the reviewed amplifier passed this test with flying colors.

But when I connected the Sennheiser HD800 headphones to it, the world stopped spinning. I had not heard these headphones from the renown Austrian manufacturer sounding so well ever before. There is something about this setup that makes the HD800 sound more resolving and more dynamic than with any other devices. Maybe this is not the level of the best planar (orthodynamic) headphones yet, but it is not far from it, and at the same time we get something that the former type usually lacks: richness of the sound.

The device repeated the same trick first with the AKG K702, and then with the extremely difficult to drive, the old Beyerdynamic DT-990 Pro headphones. The high impedance of the latter forced me to set the gain switch to the "high" position, but that's what it is for.

I could hear the characteristic features of each of these headphones models, but they all sounded better, richer, denser, more precise, nicer than with almost all other headphone amplifiers I know. This is one of the few cases of a perfect match, just like when once I connected the AKG K271 to the Funk Tonstudiotechnik LAP-2.V3.

Outputs | HEADA is an extremely versatile headphone amplifier. It offers two inputs, including a balanced one, a through (bypass) output, but above all three different headphone outputs, including two balanced ones. These outputs offer different sounds. The biggest difference is between the unbalanced and the two balanced outputs, but I noticed also a difference between the two balanced ones (!).

The TRS output (the so-called "big jack") sounds more blunt than the balanced outputs. The treble is rolled off with it and the resolution is not that good. The difference is so big that it is worth replacing the cable in your headphones with a balanced one. Such an investment will pay off with a more saturated and clearer sound. This clarity will not become brightness, but you’ll be simply offered more information. With brighter recordings, the large jack offers a slightly calmer, softer sound. However, some of the music is lost somewhere with high quality recordings when using the TRS output.

The comparison of the two balanced outputs was more interesting. This is not the first time I hear it, so perhaps it is a characteristic feature of these types of outputs - one four-pin XLR and two three-pin ones. And the difference is the same as between the unbalanced and balanced outputs, but not as significant - it’s maybe 10%. But with this class of devices, every percentage is important. Therefore, whenever possible, it is worth ordering a balanced cable with two XLR plugs.

| SUMMARY

There are many headphone amplifiers on the market, even in the higher price range. After all, we live in the headphone world. Most of them have a built-in digital-to-analog converter, which increases their functionality. HEADA is "just" an amplifier. But compared to other designs, it stands out with a few features: design, the presence of balanced outputs and a classic Japanese craftsmanship.

But not only that - it is one of the few headphone amplifiers on the market that work perfectly with any type of headphones. With it, we get an open, resolving sound that is both delicate and non-offensive. This is not a "wow!" sound, but one that we truly appreciate in the long run. And the HEADA works fantastically with the Sennheiser HD800, which performed with it in such a captivating and immersive way for the first time in my life.

| DESIGN

The Aurorasound HEADA is a compact headphone amplifier, integrated with a power supply. Its housing is made of aluminum. A wooden box is placed on top of it - exactly like it used to be done in the McIntosh and Marantz devices. The wood looks like a walnut, and the aluminum comes in a natural silver color, contrasted with a black volume knob. The LED on the front panel draws attention with its color - it’s purple.

The device could as well be developed without a wooden housing, because the sides of the aluminum chassis feature aluminum heat sinks, which would then cool down the device more effectively. But there are no transistors bolted to them - the whole chassis acts as a heat sink for active elements enclosed inside.

The circuit is built on several printed circuit boards: one for input, main one, four with amplifying modules and a power supply. The input signal is switched in the Omron relays and sent to the main PCB via short interconnects. The signal goes there to the input buffers - Burr-Brown OPA604AP integrated circuits - and then to the great-looking rotary potentiometer of the Japanese company TKD (2CP-2500).

This is one of the best potentiometers of this type on the market, which uses conductive plastic instead of a resistance path. Let me remind you that one can find it in the Octave JUBILEE PRE, costing well over PLN 100,000, as well as in the even more expensive Kondo Overture II.

The signal returns to the main PCB, and then goes to vertically connected amplification modules (AMP2). There are four such modules because the output is a balanced design. Low-noise transistors were used there, and there is also a buffer in the output stage, the so-called "line driver": the Texas Instruments LME49610 integrated circuit. The whole is powered by a high quality linear power supply, with symmetrical positive and negative runs, featuring many Nichicon Muse and polypropylene Wima capacitors. The whole layout is very nice. The power supply is made in-house and it is a discrete design with Burr-Brown chips in the auxiliary section.

Let me add that the amplification modules were designed in 2013, and the other circuits a year later. ■

Technical specifications (according to the manufacturer)

Rated output:
• XLR – 2 W / 40 Ω | 800 mW / 600 Ω
• TRS – 1 W / 40 Ω | 240 mW / 600 Ω
THD+N: 0.004% / 1 kHz
Input sensitivity: 1 Vrms
Input impedance: 47 kΩ
Frequency range: 10 Hz – 120 kHz (-1.5 dB)
Power consumption: 40 W
Dimensions (W x H x D): 260 x 250 x 100 mm
Weight: 3.5 kg