QES Labs HPBA-2 Balanced Headphone Amplifier

General Information

It has no particular "sound", but simply lets the music through as it is, without imposing anything upon it. Perfect for the purist who seeks this. It is a product designed for the professional market, where clarity and purity are mandatory. Built by hand to last, it features precision stepped volume control, constant current drive.
Works only with balanced med to high Z headphones.

Latest reviews

Pros: incredibly fast, accurate, detailed sound.
The best SS driver i have ever tried.
Cons: Available headphones are very limited
You should consider this amp as a system like a STAX
This is the review of Current-drive headphone amp HPBA-2 LE 47.

At first this is my first review on the internet and sorry for poor English
I am not affiliated or received any money for this review
I am a just music listener and audiophile. Never worked as a professional music worker


I searched and tried several headphone amp to upgrade my amp.
Among them there was a remarkably good sound amplifier
But that amp was not the amount I could buy. And I was told that current-drive is used for the product.
Since receiving that explanation. I started searching an amp works as a current-drive.
Then finally found this amp QES HPBA-2

Encounter with HPBA-2
For the first time see specs of HPBA-2, I thought what a strange amp.
Input connectors are only XLR (NO RCA)
Output connectors are the same (NO TRS Phone)
Output impedance is ridiculously High (164ohms)
But, In contrast to these strange specs, everyone highly rated this amp. And the features mentioned in these reviews reminded me of an amp I mentioned at the introduction. For example, such word as ‘accurate’ ‘fast’ ‘non-colored’
So I believed these reviews and contacted Val to know furthermore information.
He gave me a list with written base price and every options I can choose.
At that time I was already deciding to order. And I ordered and paid by bank transfer.
And Val started making amp and it takes 7 weeks then arrived at my home.

Sound of HPBA-2

After received my package. I opened it and started to listen with my reference headphone HD600 (modded). As soon as I start listening I found the sound is incredibly realistic, fast, high resolution. These were consistent with the features written in the read reviews.

This amp accurately outputs what input was.

If input is natural, it outputs as natural. If input is artificial, it outputs as artificial. This makes me recognize sound effect like a chorus or reverb.

As I wrote, this amp analysis sound from every aspect. For example volume dynamics, sound context. How to overlap sound. This amp reveals everything in the sound.

And I changed headphone to HD800. It gives more micro and macro dynamics. Soundstage is unbelievable large but less bass, and vocals are a little bit far away.

Then changed it to a beyerdynamics T1 1st gen (XLR mod) this is well known for difficulty of drive. But HPBA-2 drives it perfectly. I could hear beautiful treble. Especially female vocal are well expressed. Compared to HD800, less soundstage, more realistic tone colored.

Then after a while I bought a ZMF Auteur. This is the headphone with similar tone to HD600. For me this tone is natural and neutral. The difference is Auteur has wider sound stage. Faster response and better bass quality. I consider this headphone is a perfect upgrade of HD600. So it has been my new reference headphone. As written this headphone provide natural and neutral tone. So combo of HPBA-2 and Auteur provides

Extremely natural and neutral tone.

So I highly recommend this combo for any kind of serious listening


HPBA-2 made by QES Labs is not different from previous review. Great amp

It sounds accurate, fast, and detailed. It sounds better than all the amps I tried so far.

Of course There is a major disadvantage that most headphones cannot be used. But if you have high impedance headphone made by companies such as Sennheiser, Beyerdynamics and ZMF and want to improve their sound. This headphone amp is worth to try. Recommended

Thank you very much for trying to understand my poor English and reading review



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Thank you for the review, looks like a quality amp. It looks like something out of a Pro Audio studio, tough and well built!
Pros: The best headphone monitoring system you can buy even for audio mastering purposes.
Cons: nothing that comes to my mind
Here is my personal review of HPBA-2S fully implemented by Qes Labs.
But first I want to point out some things.

-I come from the world of professional audio.I don't consider myself an audiophile in the true sense.
I have always tried and continue to seek the maximum of transparency and neutrality coming off my sources.
I did audio mastering for some years so you can imagine what kind of approach i have toward the monitoring of a
source be it a record made finished, a mix to master or a high resolution audio file.I always look for the most
analytical analysis possible.

-In the years I've used various types of headphones and most different pro amps.
From the simple analog amplifier contained in the console, in the DAT recorder to the current amplifier
built by professional firms such as SPL and Lake People.
Headphone used are sony mdr 7509hd, Beyer DT 880 600 ohm, AKG 270 studio, AKG 271 Studio, AKG K701.

-If I came to the choice of HD600 headphones and i consider them my reference cans there are several reasons.
I know the HD600 is an audiophile headphone, but when I started to question through
email some of the most renowned mastering engineers a couple of them
answered that the Sennheiser HD600's might be the one that suits my needs
These 2 guys are named Steve Hoffman and Bob Katz.About Bob Katz
i can clearly say he's one of the best mastering engineer in the world.And he's considered a guru in his field.
He has written a book that many people (myself included) in the professional world consider the bible of professional
audio.He's always very kind with his advices and suggestions.He is a real fan of headphones.

-I am not paid or in any way affiliated with Qes Labs.Before making any statement
on a device i do very specific and deep tests.I never ever say something because i was told
or because I saw a picture on a forum.Before i made the purchase I had the chance to try the amp with my headphones
and my cable for about 6 hours.So I made a pretty clear picture of how the hpba-2 sounded and sounds.

-All coloring devices or a device that leaves its own sound signature does not satisfy my sound needs.
This is a professional device.Conceived for a fully balanced circuitry
and built with the aim of monitoring without any sound coloration.
the device is according to EEC and has 2 years warranty.

-This is a machine made just for headphones at medium-high impedance (from 300 ohms up)

-My source for the test is starting from my Lynx L22 card connected with aes ebu to my mastering grade
Stereo 96 Mytek dac.Mytek is a company well known in the pro audio world and their converters
are found in many mastering studios.The cables connecting the dac to the hpba-2 are 2 custom cables
made of an an alloy of silver, copper and gold cryo treated.All the connectors are Neutrik XLR.
Before buying these cables, I used professional vovox cables, Mogami and van den Hul.
The cable of the hd600 is made by of ALO Audio model SXC terminated with Furutech XLR connectors.

-My headphone volume is about 80-83 db.At this level of sound pressure
the response of the human ear is almost flat (according to the theorem Fletcher-Manson)

-Before buying this amp I was able to use a SPL Phonitor and a Lake People G100
my faithful amp for more than a year.Both are professional products.

That said here's my review:

As you got to see the HPBA-2 is constructed in a stylish, functional and above all strong.
As requested to my personal specifications all internal connections are pure silver.
The connectors are Neutrik gold.The main and only reason of my purchase was solely to be able to use
a fully balanced headphone system with the most neutral frequency response.
I've used various reference recordings, but the one i've used most
is the DVD audio version of "The Nightfly" by Donald Fagen.
The DVD contains a lossless track (MLP) in stereo 24-bit 48 kHz.
I really listened to this record a lot of times.I want to point out that this record was used (especially in its first version on CD)
by many audio engineers around the world to calibrate sound systems or just test the audio system of a recording studio.
It's a masterpiece and a reference recording in the pro audio world.

The stereo image is really remarkable.You can clearly distinguish the location of all instruments within the mix.
The image is almost trimensional with a clear separation between the front and back
of the source you are listening to.What impressed me more apart from the transparency and neutrality has been
the transients response.Especially on the kick drum and bass.In the higher dynamics moments they clearly alert you of their presence without being boomy.
Dynamics are really really strong and the response to transients is very clear and very very precise .Much faster than my previous amp the Lake People G100.
The advantage of the concept of constant current drive and balanced connection is something you really feel and listen.
To be honest I begin to feel the dynamic "limits" of my hd600.Transparency neutrality,clean sound and dynamics are the main charateristics of this piece of gear.
The sound spectrum comes across its width without particular preponderance for some portion of some frequencies.
The timbre is very neutral and very very balanced.Obviously excellent recordings sound excellent without any flaw.
The bad ones are mercilessly vested with all their flaws.I can clearly hear reverb tails, I clearly hear if there is a problem of phase shifting (reversed phase),
I feel perfectly as I had never happened before the pumping of the compressor in some records that weren't properly mastered or mixed.
I clearly hear click or wrong fades.
To summarize i can state that i have a very very precise picture of what comes from the source.

The hpba-2 fulfills my needs for monitoring the source without any sound coloration.Really a great product!

I think that this product is in the same ballpark as the b22.With the difference(according to a friend who is also a mastering engineer that has tried both amps and whose ears i trust a lot) that the hpba-2 is built and conceived to be a reference pro monitoring system.The b22 is really an excellent product but it belongs to the audiophile world.
I'm not here to say that one is better than the other.
I only want to say that my goal was to a have a pro balanced headphone system without any sound coloration.
That's why i bought the HPBA-2 mde by Qes Labs.

I hope you'll satisfied with all the curiosities about this wonderful device.

the most revealing chain is
Violectric V800 DAC --> HPBA-2-S Amp --> Sennheiser's HD800
mytek 96 dac is sonically inferior compared to the Violectric.
Don't use the hd650 because it tends to forgive or hide flaws in the recording.
This is not good for mixing or mastering.
If you don't want to buy an hd800 you can use and hd600 with both internal and external foams removed from the drivers.
here you can see how to do it:
Please note that hd600 has a great benefit to be driven balanced.
So use a balanced silver cable with the hpba2s
I've mastered more than a record using my daw and the hd600 with the hpba2s
I hope that helps.
all the best
Ok thanks Francesco, any other chain you recommend? maybe something less expensive?
what about the Benchmark DAC1, could i use it's included headphone amp for my purpose?
also, is there a huge difference between HPBA-2 and HPBA-2-S?


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