Here are some opinions, experiences, reviews of the amplifiers, as well as links to forum posts. I especially like the following post about the Sirrah. Wow, from which universe do these CE guidelines come: Soldering points at power sockets which have to be isolated, transformer wires which have to be twisted etc. Do other guidelines apply to icelandic bakers? Another also remarkably destructive example, his judgement on the T8000. In this style, his contributions is a recurring theme through the head-case and head-fi forums, which read like a campaign against everything that does not have the Mjölnir label. Fortunately there are still unselfish music lovers who can comment without prejudice. Here are some of them:


Zum Sirrah

2018-08-10 Herr Reinhold M. aus Poing schrieb zum V2:

"Hello, Mr. Rauenbühler,

for more than 40 years I've been banging around with combinations of stax headphones and amplifiers and I've never been entirely happy: too few lows, and too bright highs to put it succinctly and not always quite fair.
Not so your Sirrah. I'm not familiar with your other electrostatic headphone amplifiers, but this one is a knockout. I have finally arrived at the perfect Stax sound. Thank you so much for letting me experience this.

Best wishes and good time”

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2018-12-31 Domink B. aus Wien zum V2:

Hello, Andreas,

Yesterday I came to solder the adapter cable and I could successfully put the amplifier into operation. For your information: the ESP950 runs perfectly with 580V bias and the amplifier is as good as the diy Sirius I had the chance to test - thank you!

LG Dominik

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2019-10-29 Andre R. aus Heidelberg zum V2:

Hello, Mr. Rauenbühler,

The amplifier arrived earlier. I'm listening to music on the Mac with iTunes - connected to the new RME ADI-2 DAC converter. Wonderful clarity and a great resolution unobtrusive bass. You don't even need an A-B comparison with our previous DT-770. I am absolutely thrilled. Besides music, this amplifier/headphone combination is also intended to be used for binaural experiments, where spectrally narrow phase inversions in defined pitch ranges are used to test the functional integrity of the brain stem.
Best regards and thank you for sharing your knowledge and skills with the community!

Andre R. 

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2020-01-25 Daniel N. aus Mülheim zum V3:

Hello, Mr. Rauenbühler,

I have now compared the Sirrah extensively with my SRM-006tS. Its circuitry delivers clearer trebles and a more pleasant, controlled bass. The clarity in the high frequencies seems to support the spatiality. I also hear differences in the mids, but I can't tell which one I like better. Your Sirrah beats the Stax unit. Two other people have also chosen the Sirrah in a blind comparison. So I can only repeat: Great work and a big thank you for letting the DIY community take part!

Many greetings

Daniel N.

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2020-02-01 Arnd K. aus Hamburg zum V3:

Hello, Mr. Rauenbühler,

in the meantime I have been able to listen to the Sirrah V3 extensively and would like to give feedback, as promised.
I use it to drive an SR-300 Limited Edition, which I bought as an SRS-5103 Limited Set together with an SRM-353X BK. I mainly listen to classical music (orchestral works and piano concerts), as well as EDM and House. As DAC I primarily use an ADI-2 DAC (November 2019), as well as a Chord Mojo and a self-made Ladder DAC.
The differences between the two amplifiers are clearly noticeable. The first striking difference is the different reproduction of the spatiality. The Stax draws a slightly wider stage than the Sirrah. The Sirrah on the other hand sounds more controlled, especially in the bass.
Overall, the reproduction is more calm and clearly defined. With complex works and somewhat higher volumes the sound image remains clear and "doesn't collapse". Even EDM and House are fun to listen to, here one clearly notices the better control of the Sirrah in the bass range. The output power in combination with the L300 is clearly more than sufficient.
I am very satisfied with the amplifier, at this price there is no reason to even consider a Stax.

Many greetings
Arnd K.

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I have been reading here with interest for some time now. Now I would like to make a contribution to it. I have been working with Stax headphones and their amplifiers for more than 15 years. SRM-3, SRM-006T, SRM-007T to name a few. I have listened to the Lambda Nova Signature, Classic, L700 and currently the SR-007 MKI. What had always bothered me was the bass, which was more or less too weak for my taste. I became attentive then over this thread to the amplifiers of high-amp. After contacting Mr. Rauenbühler, I decided, admittedly with some scepticism, to buy a Sirrah. A decision that I have not regretted until today. Not only does the Sirrah have a rich structured bass, but it also outclasses the Stax amplifiers I know in other points. Be it the richness of detail, the clear, clean sound image, the impulse response, the Stax amps can't keep up. A great amplifier that is more than worth its money.

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Zum Antares

2019-11-16 Martin D. aus Brabrand, Dänemark zum Antares V2:

Hi Andreas

I would be pleased to give you a short feedback on the Antares amplifier:

I will compare it up against my Stax SRM007 + SR507: The sound is  more open, detailed, but also more forward. This is great. The downside  of more forwardness is a chance for it to get a little shouty in your  face sometimes and lesser 3D effect with som CD's. So the SRM007 has  more deapth and it is easyer to place the players in a room. My further  positive impression is that the Antares has a fuller sound signature and a fuller, deaper, more punchy bass. So in many ways it is a leap  forward to the better. I am fully satisfied, and will recommend your  services anytime to other costumers.

Best regards, Martin


2019-12-30 Herr Benjamin T. aus Witten zum V2:

Everything arrived safely, thank you very much!
I have also heard about it extensively at the WE.
Compared to my modified T1 and a 353X, the Antares resolves ticking more clearly and impresses with a wider stage and a very nice locatability/separation of the instruments. All in all, I would classify your amp - although it is a tube KHV - as very analytical and neutral. Your amp is predestined for professional and studio environments!
 On my T1 according to the Prof-X Blog the modification of all 4 stages was done: CSS Mod + EC99 tubes, link:  

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2020-02-20 Herr Frank H. aus Salz zum V2:

Hello, Mr. Rauenbühler,

the Antares has arrived safely, I tried it today =>
1: He stays!
2: The amplifier sounds simply stunning, at last an electrostatic headphone "sounds" as it should, A concert pitch A is an A, not a bowed one, a viola can be recognized as such and not half a violin, 
a double bass also has "bass", the creaking comes across frighteningly realistic. The three-dimensionality, although already very good on my Sigma with the old Stax, has been improved.
More level is on top and what is especially important: nothing "annoys" me, with my old station wagon (SRM 006T) I could only hear for 1 hour, then I was tired, it was just too much "chattering".
 Now I have to tear myself away from the music, I only felt this way when I listened to it through the speakers.
A big compliment!
 with warm greetings from a satisfied buyer:
Frank H.

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Zum Alpha Centauri

2018-02-23 Herr Norman S. aus Hattersheim schrieb zum V7.5:

Hello, Mr. Rauenbühler,

sorry for not getting in touch before: The amp arrived here yesterday and I could only now tear myself away to write a mail!
The device is wonderful and I would like to thank you again for the fast handling!
Many greetings

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2018-11-15 Herr Florian Z. aus Kerpen-Buir schrieb zum V8.0:

Hello Mr. Rauenbühler!

The device works perfectly, I heard on Tuesday evening, as well as last night.
Since I changed my SRM-T1 3-4 years ago in a longer phase (electrolytic capacitors, other tubes), I was very satisfied, also, and especially, compared to an extra purchased 2nd SRM-T1 in original condition.
I listen with an SR Lambda Signature and a (rare) SR Lambda Pro, i.e. not a 007 or 009, or similar "modern (500/700, or similar)" or "big".
Just last night it became clear just how big the jump from my, in my opinion, really good SRM-T1 to your Alpha Centauri is.
All the nuances that I had to "work out" with my device can be heard here as a matter of course, ... and even more.
 This weekend I would like to listen to 2 or 3 tracks that I have heard less frequently, and then listen to them with my SRM-T1.
It is precisely this retrofit that will clearly document the class of your amplifier; then the differences will become more tangible.
There are a few things that your amplifier seems to be clearly differentiated from other amplifiers, ... more dynamic levels, more accentuated fundamental range, deeper, clearer bass, terrific transparency of the entire spectrum LEVEL at even low levels, ...
 On the other hand:
In any case - and this is something I'm thinking about - the depth of the room doesn't seem to be as pronounced as with the SRM-T1 (in "my" version, with my changes). Whether this is due to spectral reasons, to the mains phase (often observed with other devices), ... is not quite clear to me yet.
However, the "arc left/middle (incl. depth)/right" with your amplifier is more closed, more homogeneous, and that tends to seem "more correct" to me, that's for sure. I also think about other tubes. Which types would come into question, Mr. Rauenbühler? Are there any other customers who have given feedback, tips or advice on the subject of tubes?
A very impressive device as it is, my deepest respect, Mr Rauenbühler.
I am very happy that I decided to buy it.
With kindest regards

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2019-05-15 James K. schrieb zum V7:

Dear Andreas,

thank you so much for your help and support. I finally managed to  finish the electrical side of the alpha and listen to it for the first  time a few minutes ago - one day after my birthday. The improvement in  sound quality over my stax srm-006mk2 energizer is incredible.  I always felt the 006 struggled to drive 007a earspeakers. - the 006 sound had  poor bass, was mushy, lacked dynamics and solidity, the sound was often  just not fun or musical it was just sound. Turning up the volume did not improve matters and the bass just got mushier.  The first few minutes  listening to the alpha shows all these problems to be resolved. I can  listen at low levels and get detail, dynamics and bass. The sound is so  much more alive than the 006. Im so glad I started this project and I am so glad you put your designs on the web. Thank you, thank you.

My implementation uses 50ppm 1% resistors throughout, Teflon tube  and headphones sockets, EH 6sn7eh gold valves, Cardas hookup wire and a  tkd potentiometer. The power supply uses 2 mundorf supreme caps and 1  mundorf ZN for the 580V.

Best wishes and I will send some photos when I have the case finished.



2019-08-13 schrieb Christian F. aus Karlsruhe zum V9:

Hello, Mr. Rauenbühler,

to your Alpha Centauri after all. The KHV puts my Stax in a much higher league. The fine resolution paired with infinite power is really fun. I am always thrilled!
Many greetings,

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2019-08-25 schrie Stephan W. aus Berlin zum V9:

Hello Andreas

So after some initial doubt, I'm now very excited and would like to purchase the Alpha Centauri.
After a quite extensive weekend with a Stax monitor, a modified T1 and the Alpha...009s and Lamda pro....HQPlayer feed-lks004 Dac... vibex current filter etc...
The Alpha did extremely well against the studio standard sr monitor. But only after proper equalizing in Roon with the Lamda pro.
Which is a pity that the case is so light and rattling.  The sound is enormous with heavy weights. Of course the case would be more expensive but an urgent upgrade. In the end that was the only reason why I thought about returning the Alpha and building it myself, but in the end I'm too lazy and very happy about a solution with on-off switch.
Best regards


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2020-09-07 schrieb Tor aus Hägersten, Schweden zum V9:

Hi Andreas,

I have own many Stax amps such as SRM-252, SRM-006T, and a modified SRM-007T.
A big improvement in sound was made when I purchased a KGSShv and a KGSShv Carbon.
These two amplifiers are fantastic sounding and the Carbon is just amazing!

I'm a tube guy and even if both these amplifiers are fantastic I started to miss the sound from the tubes.
My intention was to buy a Blue Hawaii until a saw some people mentioning Alpha Centauri in different forums.

I'm running two headphone setups:

Metrum Pavane dac - KGSShv Carbon - two Stax SR-007mk1

Modified Nad C501 dac - KGSShv - two Stax SR-007mk1

I'm going to replace the KGSShv with the Alpha Centauri.
As You can see I'm very fond of SR-007mk1 (have four of them with the right serialnumber)

The parcel arrived on Saturday and everything was in perfect condition.
I tried the amp both with the Nad dac and the Metrum Pavane dac.

The sound signature is neutral with a very clear presentation. One of the most clean sounding amplifier I ever heard.
Compaired to my heavily modded  KGSShv Carbon amplifier, the Carbon has more weight and punch at the  lower end. Digs deeper in the bass.
The AC sounds more light weighted  with a little more clarity in the midrange. Both amps have the similar  resolution at the top end.

Thanks for making such a fantastic amp and for the price it's a bargain!

Med Vänlig Hälsning / Regards



Einige Forenbeiträge:

The Alpha Centauri arrived last Saturday. Optically, the spartan design is certainly not everyone's cup of tea. I still see potential for optimization here, but for me it is of secondary importance. The interior construction makes a neat and solid impression, a generously dimensioned transformer delivers the required power. But you can really go into raptures when you hear it. In the meantime I have tested extensively on the SR-007 MK1. A modified TEAC VRDS 25X serves me as source. It was hard for me to find something I don't like about this amplifier. Maybe that the upper bass/lower mids are a bit more accentuated, while the trebles are more subtle. But everything is still in the green zone. With acoustic material the emphasis in the upper bass range is even advantageous, because a portion of warmth flows into the sound.
Transparency and clarity over the entire bandwidth is very impressive. As clear and pure as a fresh mountain stream. When you switch from a Stax SRM-007T to the Alpha Centauri, it's like lifting a veil. Instruments are neatly separated from each other and are clearly visible.
The bass is powerful, dry and deep. I mean really deep. Suddenly there are sounds from way down there that I had never heard before. At higher volumes it can happen that you get goose bumps.
And the space! The instruments are displayed in the room so that one is almost tempted to reach for them. With a lightness and looseness, even in large orchestras, the individual instruments are separated and assigned to their place on stage.
For me without a doubt an amplifier that leaves everything behind and raises the listening pleasure into another class. Correction, not another class, another world. And all this for the price of 1500 Euro!
The criticism in the open-end forum is not really understandable, especially the criticism on the bass. But maybe you have to listen to the Paltauf to understand it.

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I've now had the opportunity to hear the Alpha Centauri, and can only confirm what babayaga said. It's breathtaking how much detail the amplifier comes up with, which makes listening to it a whole-body experience. The Stax amplifiers have to queue up far behind, even Malvalve and Co. have nothing more to say

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Comparison kgsshv Carbon and Alpha Centauri V7.5

For a few days I had the kgsshv Carbon as my guest, THE opportunity to compare it to the Alpha Centauri. According to the praise that can be read in the relevant US forums, I expected a high-flyer here, but the result was rather sobering.

First to the advantages of the kgsshv. If you unscrew the lid, you look into a clean and professionally constructed interior. The construction reminds more of a marketed product than a DIY device. The sound of the kgsshv convinces with a powerful bass, which is on par with the Alpha Centauri. Unfortunately, that's it with the advantages. In all other points it is inferior to the Alpha Centauri. Be it the matte sound, the flat sound or the lack of musicality, it couldn't score here. It's not that the Carbon plays worlds worse than the Alpha Centauri, even if the terms dull or flat suggest it, but that it's rather close. The kgsshv is not a bad amp and I would prefer it to any Stax amp, but once you know the Alpha Centauri, it's not really interesting anymore. The hype about this amp in the US forums is only because they have never heard of the Alpha Centauri, so they don't know what else is possible. And to charge 5000 Euro for a DIY-amplifier is borderline, not to mention that it is only a 2nd choice.

The Alpha Centauri has now been extended by a pro power supply for an even more powerful bass.

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With permission of all concerned, I am allowed to print here the comment of the owner of one Alpha Centauri and one Paltauf who wishes to remain unnamed. Questions about the devices should be directed to the manufacturers directly, so there will be no confusion due to silent mail.
Have fun reading!

"Subject: Andreas Rauenbühler alpha centauri V7.5 with per power supply, Paltauf and Inexxon Sirius

Hello, Mr. Rauenbühler,

thank you very much, one day delivery time, that's quite something. Case screwed on, tubes stuck, it's the ones with the gold pins, connected and listened to with Lee Ritenour alive in LA and Lynn Stanley Moonlight Sessions Volume 1. Fusion and dynamics meets powerful voice with jazz accompaniment of the finest and dynamic peaks especially in the bass, this is true for both cds.

First the sr 007 first series, for which the alpha centauri new generation is actually intended. I have never heard the sr 007 so powerful, controlled in all ranges especially in the bass, no distortion whatsoever, certainly the sr 007 is darker than the sr 009. it dominates the sr 007 in all ranges. This doesn't seem aggressive and overdone. It's perfect for him. The sound image has a certain slight dryness, which I like very much. The stage is wide and the staggering is excellent. An absolutely harmonious combination. The same with the Paltauf with a big power supply and even better tubes. Perfect, best resolution, a depth that is abysmal. What is immediately noticeable is that the Paltauf moves the instruments a little closer and has less stage than the centauri. That's immediately noticeable, but the depth staggering is better. It's more three-dimensional, the centauri more two-dimensional, which shouldn't sound negative. Why? The approach of the Paltauf is a different one. The dry and extremely precise reproduction of the centauri scores here. It's so precise and doesn't swallow up anything, but with more stage, the musicians are still standing at a clear distance from each other, creating your freedom, just as it once was on stage. The bass is extremely dry, which I love and which is an advantage with some music. The Paltauf has of course more distortion, but the depth, just amazing. 3d versus 2d.

Now to sr 009 first at the Paltauf. It is the miracle of resolution and has an even deeper and more exact bass than the sr 007, I don't know how the sr 009s can beat this. Due to the enormous depth staggering of the Paltauf the sound of the sr 009 is of course enormously supported. If then 3d, then with the sr 009. stage does not have to be here, depth, depth and again depth. I compare this with a triangle, whose apex reaches far down, it doesn't go deeper. So the stage gets lost a little bit. But that seems very balanced and perfectly coordinated. This is noticeable in the bass and drums, but also in the voice. Everything stretches more downwards, so that this enormous spatiality comes into its own. The Paltauf has a slight tic in the direction of minimal sharpness on trumpet and saxophone, but convinces here with volume. For a pure tube amp but clean and very controlled.

The sr 009 on the cenauri, direct shows that the sound extends to the right and left and is looking for its foundation here, not so much downwards. Especially with Lynn Stanley this becomes clear, jazz orchestra in its perfection, of course the stage has to be here, this has nothing to do with combo. The voice is different, less deep, but supple and controlled. All instruments are reproduced exactly, nothing gets lost. The bass is deep, of course, but is caught more and is clean and structured. If you like to listen to a dry drum set with the necessary volume, this is the best place to be. With the Paltauf, volume is even more in the foreground, one could also say that the centauri is more finely drawn.

The sr 009 delivers its best performance so far on both. Mr. Schulze's sirius plays a bit brighter in thought and underlines the absolute resolution, which I would attribute to it from memory. It has more of a centauri feel to it than a paltauf. Especially volume, power and depth characterize the Paltauf and therefore it is the ideal companion for the Paltauf. I dare say it was made for the sr 009.

In terms of performance, the centauri is convincing all along the line, that's all it needs to be, on the contrary, the set-up is perfect. I tend to claim the slightly flatter display for the sr 007, the depth of a sr 009 doesn't have to be, and so I tend to like it a bit better on the centauri. I had deliberately bought the centauri for the sr 007. The centauri does not have the necessary power and fine detailing for it. Of course there is no ranking, both have the advantages as described and stand for themselves like a rock in the surf. The centauri is a hybrid, perhaps the best solution of the 2 worlds. Nevertheless, I dare to say that the paltauf forms the symbiosis for the sr 009. Anyway, the sr 007 now has a class, so I can understand why some people think it is the best electrostatic. I cannot say that Paltauf and centauri serve equally well for all electrostats. This is still to be tried, but what I can say is that sr 009 and sr 007 both have their advantages. There is no better way. I heard an lcd-2 on the luminare and hd 600 with cardas cable with this music last night. There's a world of difference. I can underline that both manufacturers have created their respective optimum without competing with each other. It makes no sense to think better or worse in this term. Both are so fascinating, one a controlled staggering with depth and 3D effect, the other a controlled stage with exact delineation and a homogeneity without losing in the bass. It's interesting when you screw on both units and take a look at the construction, at Paltauf it's all paired with a battle of materials and continues in the separate power supply with the rectifier tube. Simply crazy, this construction and workmanship. When it came to achieving this depth graduation and the 3D effect, this concept worked without compromise. With Mr. Rauenbühler the whole thing looks much lighter, wonderfully simply arranged components paired with lightness and an integrated very good power supply. It also works like this and the tuning for its advantages is perfect. It is a hybrid without a doubt, I think a pure transistor will play even more structured. The word heat is out of place with both. The Paltauf certainly has a certain warmer aura, but not in the sense of plasticizing, it fits well with the depth staggering. The centauri is certainly more neutral and just a bit more flat and dry, which I personally always like. I'd rather call it the geometric shape of a hexagon. Nice foundation and then formed into a hexagon at the top. That fits because of its wonderful stage. It reminds me a lot of the abyss, which also has this characteristic. In addition, the sr 009 has less width than the hd 800, which can be too much.

Mr. Rauenbühler has managed to accommodate useful components in a standardized housing. What is decisive is the fine tuning. Nothing is attempted here by force. Balance, paired with necessary force, but never overstating. Of course, it is also a bass wonder, more bass is not needed, superbly controlled. So the electrostats make both devices fun. I can imagine that the Sigmas will bring a lot more in terms of their characteristics on both. A sr 507 does its job perfectly on the paltauf, the technical stuff is thankfully lost here. The centauri is a working tool, whether black or silver is a matter of taste, the white writing on black does not convince me that much, here the gold tone of a srm t1 would be more valuable, therefore silver would harmonize perfectly with the fine applied writing. Now the Paltauf is a feast for the eyes due to the special version in 24 k gold front and the high gloss lacquered lid. Of course, everything has its price. Nevertheless, Mr. Rauenbühler was pleased to produce such a device in uniform design. It all depends on the content and the sound, which has been achieved here. The tubes used are perfect. The price extremely acceptable from the buyer's point of view. A small note, an on and off switch on the front like Birgir uses with backlighting in green would add to the value. You had already used this on earlier models, if I can deduce from the pictures. The connections in cinch and xlr, very high quality, that suits him well. His understatement does not suggest this perfection, that is something for connoisseurs. I already had the KGSS with a better power supply and internal wiring from Birgir, this one couldn't even compete with the two. Also I don't like to be tempted to think that the hybrid is the best compromise, because compromise in this area is always associated with a negative touch. pure tube, hybrid and transistor are equal and lead to new experiences especially with sr 009. nevertheless, the paltauf is for me the one for sr 009. Mr. Schulze tries with his one to emphasize exactly the characteristics of sr 009 and does not allow anything else here. That is consistent and logical. Nothing else makes sense. But depth graduation and 3D are perfect for the Paltauf, 3D I also had in mind for Mr. Inexxon's Sirius.

It could also be reduced to a common denominator, sr 009 on the Paltauf and Sirius, and with the least restriction on the centauri. I see the centauri more for the sr 007, and I'm looking forward to the sr 300 limited edition, which I expect to see at the end of May. This one could also shine on the centauri. Too bad the centauri doesn't have a normal output, it would also be perfect for the lambda normal and sigma normal. Hence my suggestion to you to try it here with a pro and normal output. It's the character of the lambda normal and sigma normal in particular that could have a revelation here.

Of course, the sennheiser heiser 60 must also be mentioned. We all know that it lacks a bass foundation, but produces the most beautiful and wonderful mids. No sr 009 and no sr 007 can get close to it. He develops more from the middle, that is his foundation and rightly so. The drums with Lynn Stanley are perfect, wonderfully dry but not at the bottom but rather in the upper range. That has something. The He 60 has bass and a very fine, even fine-drawing depth, which is so unique. The transparency and naturalness in the mids is extraordinary, there are no better ones. Perhaps exaggerating the treble a little too much, there could be more silky gloss, but it's very resolving. Again, the stage phenomenon is underscored by the centauri. Especially a headphone that scores with its mids will find its master here. Can there be more? Yes, at the paltauf. Due to the enormous depth staggering, the HE 60 now also gains noticeably in foundation and wonderful bass, bass and drums absolutely controlled and with a certain punch. That's the way it has to be. For me it is the most pleasing SR 009 and beats it in the mids. Voices are his profession, of course with the sr 009 as well, but here world class. For me it's one of the biggest headphones and is actually an integral part of any electrostatic collection, provided the amplifier can handle it. I can emphasize that 100% for the centauri and the paltauf. The HE 60 outdoes almost everything here. However, it requires an absolutely technically unmarked recording, otherwise it's no fun with it. Plasticizer, absolute no-go. It pampers at the highest level. By the way, get one from Mr. Schulze with the Stax adapter, it's worth it. Opportunities are extremely rare. Again, one can't replace the other, but you are an enrichment in any case."

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Inexxon Sirius

Yesterday, my Inexxon Sirius arrived with normal and pro socket and since my Alpha Centauri 7.5 (AC) was sold so fast here in the forum, a direct comparison was no longer possible. So a comparison from "memory", but I know my system well and there is only one day in between...
Because of the news of Mark Hollis' death, only one disc came into question as a farewell from the AC and in memorandum Mark Hollis: Talk Talk - Spirit of Eden.
I listened to it first with the Stax L700 on Sirius, just like I did with the AC the day before. The Sirius is unbelievably sovereign - the guitars more aggressive and cutting than with the AC (and that's how it's heard here), on the second piece piano and cymbals very finely chiselled - that's not how I heard it with the AC. The already touching voice of Mark Hollis comes even closer with the Sirius. I listened through the whole CD like I did with the AC. The AC is very good, but the Sirius is excellent. A clear class difference in my opinion. Something like the difference between a recording in CD resolution (16 bit 44 kHz) and HiRes (24 bit 96 kHz). If you don't know HiRes, you don't miss anything, but if you do you don't want to listen to the CD anymore.

Now to classical music: Brahms with Arcadi Volodos as HiRes with the L700 - good, but there I want to hear the one with the Sennheiser HE60. With him it sounds more harmonious. I know the recording very well and the Sirius works out nuances of touch that the AC didn't show. Piano but only briefly, as I have little desire for piano music right now.

So now to the symphony - Bruckner's 3rd Symphony with Giuseppe Sinopoli and the Dresdner Staatskapelle again with the HE60. The strings are exquisitely fine, the space enormous, the winds extremely powerful and even when everything comes together the Sirius keeps the overview. I know this symphony very well in interpretation and what the Sirius gets out of the HE60 is in a class of its own - I have never heard it like this before. Not that it was bad with the AC, but I didn't perceive this astonishing spatiality, resolution, dynamics, clarity and the singing of the strings.

This as a first impression - a Sigma Pro 404, a Lambda Normal and Lambda Signature are still waiting to be used on the Sirius. And of course a lot of music that I still want to hear with them.

As expected, the workmanship of the Sirius is first class and of course much higher quality than the AC. The power switch alone is a statement and the volume control conveys precision at the touch.
But the Sirius is also much more expensive and the cabinets and switches are probably a big part of it.
To classify the AC, which is a bit lost here: I compared the AC with the Stax SRM-717, which is one of the best Stax amplifiers. The AC was quite aloof - not the slightest chance for the 717 (belongs with Lambda Signature and Sennheiser HE60). So the AC is incredibly good for the price. But as so often, the better is the enemy of the good.

Congratulations to Sören Schulze and Andreas Rauenbühler on this great Stax amplifier! One can be proud that there is such a fine manufacture here and the direct contact to the developers is an additional plus!


PS: the sources used were: PS Audio Perfect Wave Transport (via I2S on DAC), Cocktail Audio N15 network player (via RCA on DAC), PS Audio Direct Stream DAC

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