Euterpe review by Headfonia

REVIEW: AURIS AUDIO EUTERPE – MUS(E)IC

Auris Audio Euterpe

In this review we put the Auris Audio Euterpe through its paces. We’ll learn how it performs sonically and how it handles different headphones.

Disclaimer: Auris Audio supplied the Euterpe amplifier free of charge. I only had to pay for importing it to Austria. Auris is not a site advertiser and not affiliated with Headfonia. Many thanks for the generosity and opportunity!

About Auris Audio:

Auris is a Serbian brand that mainly builds HiFi tube amplifiers, headphone amps but they also produce speakers. Their signature design always involves real wooden accents. Auris Audio was formed in 2013 with a mission to fulfil the desires of the most demanding audiophiles. Sonically and visually.

Their team of in-house engineers all have high experience in the pro-audio field and in designing audio equipment. According to their website, they all work very closely together when they approach a new project. Every single one of their products is hand-made and using the best possible components for the price. They give a lot of attention to tubes, capacitors, transformers and connectors. Many of which they get custom made to meet their expectations.

Every new product of theirs goes through a series of strict tests, to ensure they are exactly what their customers want. All stages of assembly have their own quality control sections, just like it should be. There’s nothing more frustrating then getting a dead unit, and Auris makes sure nothing faulty goes out their door.

We have covered a few of Auris’ amplifiers in the past. I suggest you read up on the HA2-SE, the Headonia and the Nirvana review to get a full picture of their products. Today we are looking at Auris’ starter tube amplifier – the Euterpe!

About Euterpe:

According to Wikipedia, Euterpe was one of the nine Greek muses. She was residing over music, and in late Classical times, she was also named the Muse of lyric poetry. She was the daughter of Zeus and the Titan goddess of memory, Mnemosyne. It’s said in Greek Mythology that Euterpe and her sister Muses have been living on Mount Olympus to entertain their father and other gods with their artistry. The Muses’ role was to inspire the development of liberal and fine arts in Ancient Greek, serving as an inspiration to poets, dramatists and Authors.

Taking this knowledge into account, it’s a wonderful name for a piece of audio equipment. Auris themselves say Euterpe is here to serve the needs and desires of the audiophiles.

Let’s talk a bit about the functions of this tube amplifier.

Auris Audio Euterpe

Auris Audio Euterpe

Euterpe uses two PL95 (Ei Yugoslavia) and one ECC81 (JJ Electronic; 12AT7) tube. It can be used primarily as DAC/Headphone amp but also as a pre-amplifier. Auris has selected an ESS Sabre ES9018 PRO chip to do internal D/A conversion. Euterpe decodes PCM up to 32bit/384kHz and DSD128. To unlock its highest performance you will have to use a driver on Windows machines. Mac OS and Linux systems don’t need one.

Euterpe has an analogue RCA input for an external DAC, as well as a full-sized USB B input to use its internal DAC. You can change the output impedance of Euterpe to accommodate different headphones. The low setting is recommended for headphones with 32-80 Ohms, and the high setting for headphones north of 150 Ohms.

The headphone amplifier uses a single-ended ultra linear topology. The output transformers are wound on a Double C nano-crystal core. They’re projected and developed in-house.

The amplifier itself measures 270 mm x 210 mm x 230 mm (WxLxD). Euterpe weights 4.1 kg net (without the PSU). It comes with an external linear power supply, that adds another 1.1 kg on the scale.

On the headphone output front it uses a 6.3 mm single ended connection. People who want a balanced output are out of luck here, as Euterpe was designed to be used single ended. As we know, it comes down to the circuit implementation how good an output sounds. There are bad sounding balanced outputs as well. Its output power is rated at 0.9W RMS.

Auris Audio Euterpe

Auris Audio Euterpe

Euterpe can be bought for 1,499 € or 1,699 $ US from Auris’ web-shop or one of their regional dealers around the world.

Package:

Very basic. You won’t get a fancy designed box or luxurious presentation. Euterpe comes protected in a massive cardboard box, well placed in hardened foam. Everything is already installed, so the tubes don’t need to be put in for a first set-up.

All you have to do is connect the outboard power supply via the four-pin connector to the Euterpe, hook the PSU up to a power source and you’re good to go.

If you have any doubts or troubles with the unit, you can check the supplied manual for help. There’s also a warranty card in the box. Auris gives you two years limited warranty for your unit. Which is nice to see, as the industry standard tends to be one year.

What’s missing in the package are cables. You won’t find a USB or power cable in there anywhere. So you’d better have those already, or you need to buy these. Someone who doesn’t come prepared, will be disappointed to make another trip get a power chord at least.

 

Auris Audio Euterpe

Build Quality and Design:

Let me start by saying, pictures really don’t do the Euterpe justice. Especially not mine. Euterpe’s design is simple and elegant in my opinion, of course you’re free to disagree. Its walnut wooden sides are smoothly finished and give a sleek impression. The amplifier itself is nicely thin and compact in form-factor. Of course it doesn’t look like your average box of an amp. It’s different. At the same time, it makes the Euterpe recognizable. Maybe you’re aware, but Auris did not come up with that design themselves. It was “borrowed” from Kennerton and their Atlas amplifier. Auris even gives credit to Valentin of Kennerton for that on their website. Euterpe’s design makes it moonlight as a headphone stand as well, so you’re always ready to put your cans on and start listening with Euterpe.

Whenever I’m getting another piece of desktop equipment, my girlfriend usually isn’t overly thrilled. But with Euterpe it was a little different. We have a lot of wooden furniture in our apartment, and Euterpe does fit in very nicely. So much, that even my girlfriend said she likes it. Audio takes home a win, for once!

From a build quality perspective I find Euterpe to almost fully convince. Corners are rounded and smooth. Euterpe stands solidly on its metal base. The only problem I’m having with Euterpe is with its volume potentiometer. Personally, I prefer one that doesn’t turn that easily. I like some extra rigidity to fine-tune the volume levels more precisely. With Euterpe I feel it is rotating too easily. I have been informed by Auris, that this issue has been addressed and corrected in the meantime. So all new units will have tighter volume potentiometers.

Control:

Using Euterpe is pretty much straight forward. There’s one thing to look out for though. To turn on your new amplifier, you first need to turn on its power supply. The PSU comes with its own on/off switch. Unless you flick that, you won’t hear a single thing out of your Euterpe. You will also have to turn the volume knob clock-wise until it makes a click. This is the final step of delivering power to your amp.

Once you’ve done that, you’ll notice that Euterpe has a flashing red light on front. This is basically a 30 second count-down to let the tubes warm up a bit. Tubes usually take a good hour to fully warm up in my experience.

On the front you have two dip-switches. The left one is labelled “Source”, the right one “Impedance”. The source switch lets you pick between A (analogue, RCA) and D (digital, USB B) input. The impedance switch gives you more or less output impedance. Depending on the position you get higher (H), or lower (L) impedance. The low setting is recommended for headphones with 32-80 Ohms, and the high setting for headphones north of 150 Ohms. I found them to make a noticeable difference.

The top of the unit bears another switch, which gives you the opportunity to use EL95 tubes with the Euterpe. Since most EL95 and PL95 tubes are almost identical, there shouldn’t be much difference in audio though. Only a test can prove or disprove that. The biggest difference between the EL95 and PL95 tubes is the higher voltage of the EL (6.3V vs. 4.5V). This means you could harm your PL95 tubes with the EL95 setting of Euterpe.

Like any tube amp, Euterpe’s valves do get hot when using. The heat-dissipation of it however makes sure, that there is enough air-flow to keep the unit itself rather cool. Most warmth dissipates on top. It goes without saying, don’t touch the tubes when the unit is running. If you want to change the tubes, make sure they’re cooled down. You don’t want to burn your fingers. While tube-rolling always be careful when you’re taking the tubes out. These things are sensible.

Auris Audio Euterpe

Auris Audio Euterpe

I listen to music at lower volumes, because I don’t want to blast my ears. Sound-output starts a bit before 9 o’clock. Shortly after 9 on the dial, channels will be balanced. Before that I’m getting some imbalance.

Sound:

One thing many tube amplifiers suffer from is noise. When using the Euterpe I was pleasantly surprised that even with sensitive headphones there wasn’t any to hear. I wouldn’t plug in hyper-sensitive IEMs, but monitors like the Trinity by Jomo Audio or 64 Audio’s Fourté Noir are running super quiet. The higher output impedance of Euterpe does skew the signatures of most IEMs away though. In Ears with a flat impedance curve, like newer 64 Audio products with LID, are fine.

I have mostly used Euterpe as analogue only amplifier, being coupled with the impressive Chord Electronics Qutest taking over DAC duties. We will go over the amp-only section of Euterpe before we cover its internal DAC section.

Euterpe is surprisingly neutral and balanced for a tube amplifier. Typical valve amps feature a lush, heavy and full sound, while Euterpe does so only to some extend. It does have some warmth in its sound, but the midrange is not particularly thick like I’m used to from previous tube amplifiers I have encountered.

The bass has good control and excellent body and texture. It is of calmer and softer nature, that sports great density. Bass goes deep with fine extension. Mid and upper bass are a bit elevated and stand out from the line. Low ends overall have nice dynamics and a rather organic tonality.

Lower midrange does get a touch of a boost from the upper bass segment, making them a bit more pronounced and warmer. This comes into play especially with male vocals, where they get more physicality. Vocals come with superb emotions, where there is enough air in them, to not sound static.

Auris Audio Euterpe

Auris Audio Euterpe

Instruments sound organic and realistic. There’s good flesh on the bones and very nice energy in the mids. Typically tube-amps have a super rich tonality, which is not as present on the Euterpe than on others. Still, the Auris does pack enough of it to not be dry and cold. Upper mids have splendid body and weight. Mids have high precision and speed. In some e-guitar solos you get the real picture of Euterpe’s energetic manner.

Resolution in pure amp mode is very nice with great instrumental separation. This is mostly due to the fact, that Euterpe has a wonderfully dark background, where every musician gets solid spotlight. Imaging is sharp and precise. Euterpe creates a sound stage that is well structured. It goes fairly wide and deep out of your head. It won’t pull you out of the scene though, it portrays music closer to you. This is more obvious with intimate headphones, like the Empyrean. Euterpe has really good layering abilities in my opinion. It keeps things well organized and structured. It manages to capture many details and enables you to distinguish between separate instruments easily.

Treble is done tastefully. I can’t detect any sharpness or hard edges in the top segment of Euterpe at all. Highs are clear and have good shimmer, yes, but there’s not much grain in these notes. The Auris does have a certain softness in its treble tones, that makes them really pleasing to the ear. At least to my set of ears.

Auris Audio Euterpe

Auris Audio Euterpe

DAC Section

When switching from Qutest to the internal DAC one thing is rather obvious. The sound does get extra sweetness. Euterpe’s DAC section does a good job at reproducing details and spitting out information, however it can’t hold a candle against the power of a high end DAC like the Qutest.

With the internal DAC you get a more intimate presentation. The sound stage does not excel as wide or deep as with the Qutest. The overall sound is more focussed and not as wide-spread. Notes seem a touch richer and a little fuller as well to me. The presentation is a smoother one with a more relaxed sound.

Resolution, instrumental separation and layering all have taken a step back. With the internal DAC you get a dark background, but it’s not black like in amp-only mode. The sound is more two-dimensional, with good, but not excellent, imaging. Also, there seems to be some mild audible distortion, which is a big no-no. With Qutest Euterpe plays cleaner, clearer and with higher resolution. It separates sharper, extends wider and deeper and overall just performs at higher quality.

When using USB B input you also need to dial higher on the volume potentiometer.

 

Auris Audio Euterpe

Tube Rolling

For those of you who want to play around with the signature by rolling some tubes. There’s some room for that too. I have on Lievens recommendation replaced the stock JJ ECC81 tube with a NOS manufactured by Mullard. I have had good experiences with Mullard so far, so my choice fell on one of theirs again.

When replacing the stock ECC81 with this particular one, you get a richer tone. More body in the midrange and an overall fuller sound. You gain more warmth and loose some treble clarity and hardness. Bass gets more texture, precision and extra weight. The sound gets more immersive, thicker, smoother and more musical if you will. Euterpe gets lusher and richer from top to bottom.

I enjoyed this tube more than the stock JJ ECC81 and since its arrival have put it in as main set-up.

As mentioned earlier, the EL95 and PL95 tubes are almost identical. Their only difference is in higher Voltage. From a sound perspective these are pretty much the same. I couldn’t hear any difference when I installed my Mullard EL95’s.

Tube rolling is a lot of fun, but you have to stay within specifications of the original tube when you perform this act. The JJ Electronic ECC81 (12AT7) is a dual triode, medium gain pre-amplifier tube. A more precise spec-sheet can be found here: https://drtube.com/datasheets/ecc81-jj2003.pdf

If you want to read more about these tubes, check out Lievens Auris Ha2-SE review, as it uses the same tubes.

Auris Audio Euterpe

Auris Audio Euterpe

Pairings:

With 0.9 Watts RMS output power, Euterpe does have enough to drive most headphones to very loud volumes. As we all know, output power is not everything. It really depends on the circuit implementation to have a great sounding amplifier.

Euterpe is designed for full-sized headphones. I have almost exclusively used over ears for this review. In Ears have only been brought out to check the noise floor of the Auris. Most of my inventory concentrates on planar magnetic headphones. Just shortly before Euterpe set foot in my apartment, I sold my HD800S as it hasn’t seen much use. Thankfully, I still have my early production AKG K240 Sextett to check how Euterpe handles hard to drive dynamic headphones.

I find Euterpe to pair better with headphones that come with a more organic and fuller presentation themselves. Overly analytical headphones such as the Diana Phi aren’t a good match in my opinion. I have used the stock tube configuration for this section, as it makes no sense to describe a pairing out of its factory setting.

Meze Audio – Empyrean

The Empyrean is definitely one of the most talked about headphones in the recent months. I got mine as a birthday present to myself. You gotta treat yourself every once in a while.

The Meze has an overall slightly darker sound, and I’m using the leather pads more than the velour ones. I like my bass a little tighter and faster. With the Euterpe you get an intimate pairing, that does not excel in sound stage dimensions. It’s a concentrated presentation that puts a quality listening experience with high levels of body and soul to your ears. I don’t turn the volume potentiometer much past 9 o’clock, as that is more than enough for my listening comfort.

You get a thicker midrange, with more weight in the notes. Lower pitched instruments particularly are heavier and denser. Bass notes have good body, dynamics and are of high quality to me. There’s plenty of resolution down low with good texture and layering.

Treble is on the calmer side, but still well pronounced. Highs have decent clarity and brightness, however, there are other headphones out there that put more decibels in that region. You get a lot of details and the Empyrean manages to put them all into their place. Imaging is one of the things the Empyrean does exemplary. It places all instruments carefully in the room and gives each musician enough room to breathe. Even during information-overloaded segments in music, the Empyrean stays focussed and keeps its structure.

Auris Audio Euterpe

Auris Audio Euterpe

HiFiMAN – HE1000se

The volume dial does not surpass 10 o’clock before it gets too loud for my taste. So there’s still enough room on the pot to go even higher for those that enjoy their music loud.

With the HE1000se you get a wonderful sounding combo. There’s plenty of body, good dynamics and great resolution and texture. Bass goes deep with a nice and full sound. Sub-bass is well formed and enjoys good rumble.

Something this combination just oozes of is transparency. The mids sound open, emotional and most of all harmonic. I love this headphone to bits, and with the Euterpe it just doesn’t stop. It’s fast, it’s precise and it is oh so musical. Body, texture, layering and speed are all there at the top of their game.

The top end is fast, energetic and clean. It’s well extended and precise, never hard or sibilant. The richness of this pairing is absolutely gorgeous and makes me just want to keep enjoying my music. Vocals, male and female, have the right kind of emotions and weight. The stage is wide and deep with a holographic sound, where the bands are performing right in front of you.

On a technical level the pairing convinces me as well. Resolution is high, rendering very fine and precise and instrumental separation is achieved very well. I can pinpoint every musician in the room, and every note appears clean and clear. I never have the feeling that something gets overlooked or smudged. This is just a wonderful pairing I can dive into on a long run.

Auris Audio Euterpe

Auris Audio Euterpe

MrSpeakers – Ether 2

The Ether 2 is one of the headphones that surpasses the 10 o’clock point on the volume pot, although not by much.

There is good low end drive in the Ether 2 when paired with the Euterpe, however I feel there’s weight missing. Bass can sound slightly anaemic and thirsty for more substance. The lows are presented a touch south of neutral with a tight grip.

What this combination does really well is create a holographic stage. The music seems to float on a pitch black background. The layering here is impressive and this goes hand in hand with transparency. It definitely brings a lot of that to the table. The Ether 2 does capture many details and information and displays them in an upfront manner.

Midrange is lighter in body and weight, but delivers good levels of speed. It’s articulate and fast, with great resolution. Where the Ether 2 succeeds in this pairing is in creating a nicely wide and deep stage, and putting musicians into place. Imaging is very good, as each instrument is portrayed with precision. Mids are neutral in richness, they are not overly dry nor rich.

Due to the missing low end action, upper mids and lower treble can become a bit forward sounding. Which can result in them having a metallic timbre at times. Overall I’m left with mixed feelings about this pairing. On one hand it creates an impressive listen, but on the other the tonal balance is just off.

Auris Audio Euterpe

Auris Audio Euterpe

AKG – K240 (Sextett)

Bloody hell, I did not expect Euterpe to handle these that well. At 600 Ohms and 94db/mW the AKG’s aren’t exactly easy to drive, but Euterpe does get them to my comfort levels and way above. I set the impedance to high and the volume knob goes closer to 11 o’clock now.

The Sextett is one of my headphones, that is pretty picky when it comes to amplification. It needs power, loads of it, but also the right kind of it. It’s no easy task to get the dynamic transducer and the six passive radiators to work well together.

Bass is tight and controlled, just like with the Ether 2 it’s a bit lighter. The Sextett is a more balanced headphone, that does not particularly favour any specific frequency range. It puts good body and emotion into its sound. The midrange is open and sounds very precise to me. The Sextett does not sound super-rich, nor does it sound dirt-dry either. It’s placed somewhere in between, to sound realistic enough.

With amplifiers that aren’t capable to handle the Sextett, I usually get a wall of sound. With Euterpe this isn’t the case though. Instruments are well separated, resolution is good and layering done well. Driven right, the K240 can put out a lot of details, and that’s what is happening with the Auris. Informations are resolved with care and brought out with accuracy.

Euterpe makes these vintage headphones from the early 1970s really sing. I mean, sure they are not close to in performance to flagships of today, but for the price I snagged them, these are ridiculously great. Sometimes it just works.

Auris Audio Euterpe

Auris Audio Euterpe

Conclusion:

Back in the day when Lieven reviewed the HA2-SE, he called it the nicest tube-amp he has heard at that time. On paper the HA2-SE and the Euterpe aren’t too different. They share a lot of their internal design DNA. When I heard about an upcoming starter amp from Auris, I was highly intrigued. Thankfully, I got the opportunity to get to know this gem. Although I would still love to compare the Euterpe against its bigger sibling one day. Unfortunately there is no dealer for them in my region, looks like a trip to Belgium has to be booked for that.

Over the last couple of weeks, Euterpe has given me many hours of listening pleasure and made me relive my tube-rolling days. The Auris manages to drive all my headphones, even the tricky ones. Euterpe not only delivers enough power to get my headphones loud enough, it also delivers the right kind of it, to make them sing.

How Auris have managed to create an amplifier with a noise floor that low still puzzles me. It is also beautifully finished and even girlfriend approved. The fact that it doubles as a headphone stand is a nice bonus. The real strength of Euterpe definitely is in its amp-section. With the internal DAC I am missing some of the magic. So bring on a high end DAC and you’ll be happy for sure.

Euterpe is my first higher-end tube amplifier, and it definitely has created a thirst for more. Colour me impressed.