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05.07.2014. Visitor Giorgio (from Italy) wrote:

HAD AudioLAB Product review

Maestral 4Stax, another great amp!

I have received this new amp for electrostatic headphones from Drazen after the great result of the Zephyr.

I’ve received some informations about it, regarding the idea and the market position of the amp, just to put it in the right position of my mind.
So, Ive tested it in comparison with my MegaHertz Guerra, a real battleship for ELS headphones:


My impressions (and Drazen comments) as follow:

Hello Drazen,
I was not been able to deepen as I wanted the performance of your Maestral 4Stax, due to a number of family issues that have left me little time for fun.
I did, however, a fairly certain idea of the amplifier, that I will try to describe you. As always, do not be offended if I will be honest about the amp. I appreciate your work and hope that my feelings can help in improving it.

From a sonic point of view the amplifier has a warm tone with excellent bass and mid-bass, deep, present and articulate. The yield is never regret a dynamic headphones, a very, very positive sensation. Even the mid-range is very well balanced and real, with well-designed male voices and transparent and smooth female voices, with no sign of bitterness. The top end, however, it is far enough back and with a not always adequate detail for the class of electrostatic headphones. Maybe a little roll-off, maybe a little poor detail ... Poor in comparison with the treble that the Zephyr shows with Stax.

This characteristic of the high range also affects the 3D of the amplifier, which appears a little closed, with no breath and airiness, negative characteristic that Stax show dramatically. The scene looks compressed compared to the Zephyr, confining all the sound inside of the head. I thought it was the fault of the valves, so I bought valves of good quality:
6N7 RCA matt finish, 6X5GT Brimar and Fivre and 6SN7 RCA.

Things have improved a little, but not as I expected. It almost seems like the kind of sound of the amplifier depends upon a design choice rather than materials (poor valves).

Of course, if you want to share your opinions with me, I will be grateful for this.

Thanks for your comment and opinion, I must read this carefully and thinking about change something in internal electrical design of this headamps (4stax).

This is obvious. And in my head I have some ideas that could “open” the amp in treble.

Hi Drazen,
the Fivre 6X5GT was a REAL improvement for the Maestral!!!!!!!!!!!!!!!!!!!!!!!! Great sound, really!! Not great space, but the general level jumps ahead!!!!

Hello Drazen,
at the end of my test about the Maestral 4Stax, I’ve changed drivers and rectifier another time, having, unfortunately, no other 6N7. Rummaging in the closet of the valves I found a 1950’s Sylvania 6SN7GTW, that I tried instead of the RCA and with the 6X5 Fivre and Tung-Sol metal base.

Well, I personally think that the change of the rectifier modifies the sound of the Maestral more than the driver in terms of timbre, but the change of driver is essential to open the scene.

Now, finally, the Maestral sounds like I wanted in terms of three-dimensionality and detail, with a really nice sound. Too bad that the valves installed cost so much!!

If you can also change something in the circuit, the amplifier will be really high level one!!!!

thank you for the lovely reviews. I’ll make changes in electrical topology witch replace a need for expensive tubes. Of course, with a desire for more concrete sound, especially in treble area.
Also, with the intention to stay within a range of acceptable pricing levels as a compact but still tube and nice sounding amp for Stax.


07.06.2014. Visitor Giorgio (from Italy) wrote:

HAD AudioLAB Product review

Zephyr… What else?

Hello Drazen,
a bit of time has gone and I was able to get a serious idea of ​​the Zephyr. So I decided to write to you. The amp mounts two NOS Marconi 2A3, one Psvane 274B, one NOS RCA 0D3 and two NOS Mullard E88CC.

Without a doubt the Zephyr is the best amplifier for dynamic headphones I’ve heard in 40 years. The listening quality with Sennheiser, AKG and Grado is spectacular, as not to regret anything ... We have rediscovered the first class of old headphones like the HD-565, HD-430, K340, RS-1, capable of giving true emotions. The silence of the unit raise from very good to excellent, depending on the headphones. The loudest are the Grado RS-1 and Sennheiser HD-565, but much depends on the quality of the final tubes 2A3.

Listening with planar headphones is very good (especially with theHhifiMan), but not at the same level of dynamic headphones. In this case it is “only” an excellent amp! Everything sounds at the highest level, but lacks a little bit of magic.

Listening the K1000, from the speaker terminals, the sound is very good in the midrange and upper-middle, but a little “poor of impact” in the low range.

With regard to electrostatic headphones, it is, in my opinion, a wrong project. No offense, I do not want to criticize you; however, the use of electrostatic headphones is limited to genres with low dynamic. Small group jazz and classical chamber music sound very, very nice, as long as you do not overboost with the volume. But if you need dynamic, 2A3 drives fast in crisis, with audible distortion. Maybe a 2A3 push-pull…

But that’s okay, I was not looking for a “first class amp” even for the ELS. For these headphones i’m very curious to hear your dedicated amplifier.

Well, what can I say? Thank you for your commitment and for your great job.



29.04.2014. Visitor Lest (from Croatia) wrote:

HAD AudioLAB Product review

The first time I’ve met with Had Audiolab was at the 2.nd Croatian Triode Festival.
I was back then only interested in headamplifiers,never heard it before.
In a variety of tube head amplifiers, the Had Audiolab Maestral One,was put up above all others.
So,the next year on 3.d Triode festival,I’ve listen it again,an there was no doubt,I bought it.
There is two years that is now in my possession,and I’m calm for ever with head-fi.
Maestral has such a detailed saound,if you didn’t now that you are listening a tube amplifire,you will be thinking that is an SS,but with all the advantages of tubes:)
The construction..well,hand maid in Croatia,only high-end parts assembled with patience and love for music;)


18.04.2014. Visitor Zlaja (from Osijek, Croatia) wrote:

HAD AudioLAB Product review

This new Cyclone GM70 is for now completed my quest for good sound and I am very satisfied.
I do not write a lot of words, but I listen to a lot of good music…..


27.03.2014. Visitor Yugas, Spain wrote:


After 5 days of shipping (I’m inside Europe too) finally I got it here!

Package is very well protected and tubes for replacemente are supplied too, very good detail from Had-Audiolab.

Built quality is awesome, it feels like a tank and it is quite heavy too.

NOS tube are about 50 years old, but they are in very good cosmetic conditions and to my ears sound very musical, not too much colored sound (in fact less than my previous Icon Audio HP8) , with a rich and sweet middle section, smooth highs and great sense of space.

This early impressions using my Hifiman HE500, wich I find a better pairing than I thought.

Later I will connect some of 300 ohm Sennheisers, HD600 and I will try to use the HD800 too, OTL amplifiers like this always provide good sound with this type of high impedance cans.


27.03.2014. Visitor Beocord wrote:


I’m seriously considering purchasing maestral III. I thought about going for woo audio or bottlehead but 24%vat+customs are quite a turnoff. Sucks how stuff is priced around here. I was looking for Schiit distributors in Eu. Pricing principle seems to be converting usd to uk pound 1:1. 737$ for schiit lyr for example. Anyhoo…I hope had products sound as good as they look. All reviews seem positive. Not just the meastral line their other stuff seems to get some praise too. Would be great if someone could compare maestral amps to some more known amps. So if anyone has something to contribute I would really appreciate your input.


27.03.2014. Visitor Azzaro wrote:


Well I have the Maestral Three standing on my desk, by me in short named the M III and listened to a variety of music. Lately I do like to listen to Ambient, Experimental and say BioSphere related music.

Actually I am not interested in the technical aspects of the M III because when things are built accurately and well inspired it is my experience that it will perform well too. People who like that type of information can look it up at http://www.had-audiolab.com/

So my focus is on the how does it manifest and perform with all the different styles of music.

First of all I have to say that this is for me the most fascinating headphone device I ever heard.

Every-time when I start listening to it, again and again it is surprising me by the sound it brings forward to my ears.

Just by fun I gave it a variety of headphones from the low cost-level to the higher cost-level ones.

I wanted to come to know by doing so what the true soul of this M III is.

In this respect I came to the conclusion that it always immediately is revealing the true character of each headphone and getting the best out of each headphone. Also this is the first time that such a thing became so apparent to my ears. And yes that makes me very happy.