HPA-nxV200 R2 based  dual mono amplifier


Dual mono (2 x 500 VA), separate supplies for input stage (2 x nx Volt One) and output stage (90.000 uF per channel).

The amp was easy to build and worked as expected “out of the box” The nx Volt Ones needed adjustment, but if you give them a proper input voltage, they behave exactly as described. The questions I had during building were promptly answered by Anthony. And had I bought the right secondary trafos right away, I would not have needed his support at all.

Listening Impressions

To set my personal bias straight: I have been passionate about Hi Fi for + 40 years, I have heard a lot of gear, including top of the line amps from Audio Research, Naim, McIntosh, Classe, PassLabs,  etc– and I am lucky enough to have a pair of very capable speakers (Audiovector SR6AA), so below I am not implicitly comparing to budget gear.

At first power on, it sounded edgy and veiled, but that changed gradually over the following 6 weeks  to transform itself into probably the best amps I have ever heard. Since the difficult start it has been growing on me. But it does need some serious burning in – and it would be unfair to judge it before that has taken place. I had it turned on 24/7 for several weeks but kept getting better over time.

Without signal, it is dead silent. It depicts a large 3-dimensional soundstage- very broad, extending well outside each of my speakers, and so deep that some of the musicians seem to be playing from behind the rear wall. It is very detailed and will let you in on even the tiniest  sounds and details – without even the slightest trace of sounding analytical, thin or “naked” . It combines the ability to place each sound source  precisely on the stage with the ability to integrate everything into an organic scenery. With good live recordings, the soundstage is huge and it is as if you could walk up there blindfolded aand still know precisely where the players are.

And somehow my speakers are now much more easy to place in my room – this amp seems to maintain the tonal balance much easier than its predecessor that needed much more support from the rear wall  -  or the low end weight would be lost.

What probably has enticed me the most is the perfect tonal balance – electric organ, trumpet,  cymbals,l etc. - are rendered with body, warmness ( if called for) detail and nuance. It renders perhaps the only quality of a tube amp that I have been missing hitherto : the low midrange “ juiciness” of voices, winds drums.

It is difficult for an amp (and speaker too, for that matter) is to render the “body part” of cymbal, hi hat etc  with the proper  sense of weight and dimension, and at the same timecommunicate  the fine nuances of the decay as the sound travels towards the walls of the room in which the sound was recorded – the aussie masters this discipline.

It kicks with a vengeance, but at the same time it retains all the detail and delicacy you could ever ask for - so macro and micro dynamics are in perfect balance, it seems. And it is infull control, whatever the music and the sound level.

All this is delivered  in a very natural, spacious and coherent way,  a way that lets me focus on the music, that comes to life end blooms in my room.

This is an amp that does everything important right.

Some have compared their “Aussie” with some very renowned gear, concluding that their Aussie was better. If I remember correctly, comparing to the gear that I have heard, I totally agree.  I believe it must be up there, among the very best.

I know I sound less than objective - but there is a reason for my enthusiasm: My Aussie  is an exceptionally communicator of music. I really do believe that something special is going on here.

Ole Thomsen



CD: Sony 707ES, heavily modified with ZapFilter
PC with S
ound Blaster X-Fi Titanium HD Audiophile Sound Card (I know, but surprisingly good)
Preamp: Own design, with DACT attenuator, relay switched signal and ground paths and selectable passive or active (AMB labs
α20) line stage) Houses a separate DAC (NewClassD).
Speakers:  Audiovector SR6AA (4 way speaker with Audiovector Avantgarde Air Motion Transformers)


Eva Cassidy: Live at Blues Alley, Songbird
Miles Davis: Kind of Blue, Sketches of Spain, Porgy and Bess, Bitches Brew, Dark Magus, Get Up with It, Cellar Door Sessions, Agharta, Pangaea
Dire Straits: Private Investigations
Hans Theessink, Terry Evans: Visions
Grateful Dead: The Closing of Winterland
Nick Bärtsch: Ronin Live
Jan Garbarek Bremen
Keith Jarrett:  Sun Bear Concerts
Eagles: Long road out of Eden
Anuar Brahem: The Astounding eyes of Rita
Cat Power: The Covers Record.

And: Thord Gustavsen, Josefine Cronholm, Zawinul Syndicate, Joni Mitchell, Rickie Lee Jones, Ane Brun, Massive Attack, Faithless, Primus…

Various classical music.



Dear Anthony,

I've installed the nxV200 R2 amplifier modules and I have to admit that they sound very well! First thing one notices is that the modules will happily deliver a lot of tight and clean bass. Next thing, is the wide bandwidth. Using a descent source, all the detail will be easily noticeable. Mids are realistic especially if one plays some jazz music, and high frequencies can be really sweet and clear. However, as many others have already mentioned one can easily tell a good quality from a not so good quality recording. Overall, I am very pleased with the modules.
Well done!
Here goes a pic of my amplifier finished. The amplifier is built in dual mono configuration with a 2*28V, 300VA toroidal transformer, two 35A/200V rectifier bridges, four 6800uF/63V/105C filtering capacitors per channel and 100nF/630V mkp bypass capacitors. I used 4.7uF/450V mundorf coupling capacitors in the input stage although my source has no dc offset. At the rear I installed a simple delay relay for the speaker connection in order to avoid any annoying noise from the power switch and/or the charging of the filtering capacitors.

Kind regards,
Kostas, UK




Hi Anthony,

Thank you for a excellent product (nxV300R2) and one more in the making, My choice fell on a 300 and I am very satisfied with that, I used a lot of time (about 9months) but when the amplifier was conceived it was all worth the Wait.

Powering it up for the first time on my modified HF-275 speakers the sound was crystal clear tight an powerful yet gentle when needed, The nxV300 was replacing a LC Audio Zapsolute 42W (pure) Class A. After a short while I had to admit I was missed some of the soothing warmth of my 15 year old Class A.



I soon realised that the sinner was the attenuator in the preamp, the distortion that it produced when installed in my old amplifier was never detected at the time.

Luckily I got myself a new Seiden 23 pos attenuator with Takman Carbon resistors and it gave me the long wanted soothing sound,

Now when I play music I soon forget about the different sounds coming from the stereo, I rather quickly start to enjoy music.

Today I had a fellow Hi-Fi addict visiting me, we played many records, both good productions and bad, ending at some badly produced pop records from the 1980s, we both agreed that the music was in focus and most of the time messed up our analytic session.

When you don't want to change record for a new one to be tested you know that the sound is excellent.


Thank you

Per Glad



Dear Mr. Anthony,

I'm extremelly satisfied with your amp modules, so I decided to build another, more powerful amp.

My friends are surprised with the sound and with Yamaha NS-1000Monitor it sounds simply heavenly. They want to see is there any subwoofer installed behind Yamahas, but...

So, I would like to inform you that I'll order new HPA-nxV500 R2 modules from you.

Thank you for all support, regards,

Boris, Croatia

An Update

Dear Mr. Anthony,

Now your amplifier is in nice setup.

Source is Sony NAC-HD1E, loudspekers are Yamaha NS-1000 Monitor and please, don't ask for interconnect and speaker cables. All wires are custom made, perhaps I can add some money to improve wires, but at this moment it seems that is not necessary to change them.

Now, what to say...?

Previous setup was with KEF CS5. Not bad at all, but pure renaissance this amp have with Yamaha NS-1000M.

You know what Yamaha made before almost 30 years. Compression cabinet, berrilium, good crossover network and that's it. Magic sound.

With nxV300 you can hear piano as piano and sax with all noises of air turbulences in instrument. I cannot compare your amp with any other amplification in my home because it cannot be compared. You can compare only similar devices which can be different in a few minor things, but in my case differences are too big to establish any good and fair observation what is better.

Simply - amp is fantastic. I have never been jazz lover. Now I cannot stop to listen jazz...

So - what's wrong?

Nothing is wrong, now finally I can hear all sweetness and detail of each instrument. Now I have all, now I have music.

Thank you for this. Good job!

Boris, Croatia



Hello Anthony.


I have benchmarked the amps to a couple of expensive amps like Krell KSA-300, Luxman M-600A, Dynamic Precision and some other amps that’s regarded to be in the higher level, and none of them had anything on the nxV500.

None of the amps where better in any area, control, bass depth, clarity, separation, airiness. nxV500 is probably one of the best amps in the world.


Thank you.

Jonas Lindholm


Evomatic AB

Karlshamn, Sweden



I recently bought some nxV300 amplifier modules from a good friend in Denmark.

I have played with Hypex Ucd400HXR for about 1 year,

but yours nxV300 improves in the whole frequency area, i'm very impressed...

We are planning to build an active speaker with your amp's in near future...


Kind Regards

Michael Godskesen 



Hi Anthony...

An little update : For 2 days ago, we made a battle between an Nelson Pass XA30.5 and my Nvx300 with Smps dual mono supply, all 3 of us did choose the Nxv300, more powerfull/dynamic, midrange was more clear and defined, but the top was even more detailed  and still as friendly sounded as the Pass, indeed very impressing...

We where all very surprised, and i'm a very happy man.......

Regards Michael.

Just listened to my new NXV 500 R2 . Its amazing -- sounds wonderful. Much better than the earlier modules. Has the missing warmth in lower midrange upper bass. Transparens is so much better also. This amps is way better than the NCore 400 I made for a friend some weeks ago. The N Core 400 sounds like a clock radio compared to this.

Erlend Sæterdal, Denmark

Dear Anthony,

We have a shoot out between the UcD180AD vs Pass-Lab Mini Aleph vs nxV200, all DIY amps driving a pair of Coral Flat 8. nvX200 sounding to best to 2 of us, more "weight", details and very good soundstage, it is really a good amp!


Khiew Chung Wah


Midas | Klark Teknik | Clair Brothers Audio Systems

Hi Anthony

We have now had the opportunity of carrying out extensive listening test with your NXV202ps modules and pleased to say this performs extremely well on a wide range of different genre of music, but seems to be quite ruthless in sorting out the poor recordings from good ones. We felt that the bass was particularly well presented and is well extended. The mid  and high range is equally good with excellent clarity and detail.

Female voices show no hint of sibilance and the dead quiet background is impressive - even though the module was bread boarded with no special attention given to the layout of the connecting or signal wires.

We compared this to a Parasound 300W/ channel class A power amp and would say the  NXV202ps  is certainly up there
and in certain areas exceeds the performance of this behemoth.

The other comparison was conducted vs our Glowmaster KT88 65W /ch class A   power amp ( which has a 5 globes rating from Hi Fi World) and can honestly say there is very little to chose between them apart from a slightly warmer sound from the valve amp, but with a more extended bass from the NXV202ps . ( We used a 500VA  transformer). This result is more or less what we expected. So there is little to chose between a   "£600" NXV202ps based power amp and a £2500 Glowmaster KT88.

We would certainly  agree with some of your other users who have posted reviews that these offer Krell / Bryston performance - but at a fraction of the price



Acoustic Perfection, UK

Hello Anthony.

I have been playing for two weeks now the nxV500 and im absolutely blown away with the performance. Not just the dynamics and the total control, but also the level of details and how it paints up the soundstage. Really impressive work and had a real guru over this weekend. He is the number one audiophile i would say in Sweden, but that might sound a bit steep. However he was really impressed and wanted to try it and build one himself. My father will soon order a similar setup.

Best regards from a very happy man.

Jonas of Sweden

I'm now using nxV500 to drive my MG12.

Thanks Anthony, you did a good job, the modules performance is very very good! Relaxed but no lost of details, especially the silky high-freq, no harshess, very smooth, pin point focus, wide open sound with very good resolution!


Kenneth Lau, Hong Kong


Hi Anthony

Well I finally have my stereo upgrade finished and it sounds sensational.

Your nxV500 lived up to every dream held and exceeded all expectations.   I am extremely satisfied with my purchase, it was money well spent.  And I'm not just referring to the quality of the sound reproduction, it is truly a craftsman build piece of equipment both in internal construction and in the professional external appearance.   Thank you for your efforts!

This amp replaced a custom made DEX amp which was in itself is a superb amp but it simply doesn't compare to the bite of the nxV500.  The nxV is so clean & crisp, I'm now hearing definition and harmonics, owing to the massive distortion free head-room, which creates perfect sound fidelity and imagery across a full range of music genres.  I spent all day yesterday listening to music.  First time in a long time.

However, this has created a problem in that the brilliance of the nxV is now overshadowing my bass power amp, which although has a higher power rating, cannot compete with the dynamics and punch of the nxV.

I know it would be a waste of time searching for a comparable power amp that will drive my JBL bass bins with the same energy of an nxV.  I also doubt I would be satisfied with anything less than the performance of the nxV, so in order to balance my system, I have decided to order a second nxV500 from you.

Cheers Rik  (ex sound engineer HSV7)

Warrandyte, Victoria, Australia

As a very happy owner of an Arcam AV300 receiver, I was looking to intoduce a dedicated poweramplifier to my setup to enjoy a superior musical experience. I'm a big music lover and didn't feel the Arcam was providing adequate power to the two font speakers. After reviewing the testimonials for Holton Precision Audio, I took a chance (without auditioning the amp) and purchased the NXV500. The aim was to to buy an amp that would provide a world class solution at an affordable price, and I must say, this NXV500 amp is one of the best things I've ever bought!

The configuration I purchased included dual power supplies to provide a no comprimise solution, housed in an elegant custom built chasis provided by Holton Precision. The NXV500 is connected to my Arcam and drives the the two main speakers (KEF Q7) whilst the Arcam drives the rears.

And how does it sound? Simply awesome! Power, precision, poise, drive - this amplifier makes me smile! And thanks to the high damping factor, the way it drives bass with such precision and control is truly astonishing.

Nearly all my audio equipment will be recycled over time - my Arcam, my Kef Q7's, my Squeezebox Touch. I do not intend to recycle the NXV500.

On a side note, Anthony's service is excellent. Aside from designing an outstanding amplifier, he always is available to take calls and has integrity.

I cannot recommend Anthony's designs, quality and service enough.

Congratulation's Anthony on developing a wonderful product. I wish you and your business continued success.


Melbourne, VIC, Australia

Hello Anthony,

At first thanks for your kind support in the whole phase of my AMP III project.

After a long search to a High End Amp module, which suits to the rest of my electronics and replace my Audionet AMP V multichannel amplifier, i am glad that I found your perfect build nxV201PS & nxV202PS amp modules.

Because I have replaced my main speakers in the past to a set of Avantgarde Acoustic Duo Omega Horns and build therefore a set of 300B SE mono blocks, i only need three of the five channels in my old Audionet AMP V.

So a new DIY project was born.

To make it short, your modules are absolutely awesome. With my use of the Mundorf M-Lytic AG  power caps, I missed nothing to my old amp, quite the contrary.

The so important mid tone for the center channel is so perfect, chapeau!

Also the very precise bass is fantastic. Please keep going on with your wonderful stuff.

Best regards from Germany,


The HPA-nxV201ps modules got here in great shape.

Thanks Anthony!
very surprised by the bass performance! I was fully expecting outstanding midrange and HF performance and was not disappointed (you're being compared head to head with Krell and Bryston) but the bass was completely unlike any mosfet output stage I've ever heard, and honestly the first listen have me so excited that I could go out to my roof and yell... What great amps!

3 cheers for HPA!

Bill Weir

North Carolina, USA

Hi Anthony,

I've been testing a pair of your nxV500's in my current reference system which comprises of:

B&W 800D Floorstanding speakers ($35,000 a pair)

2 x Classe CA-M400 mono block amplifiers ($22,000 a pair)

Classe CDP-202 CD player with inbuilt volume control ($11,000)Kimber Select Interconnects and Speaker Cables ($7000)

And previous systems consisting of Mcintosh, Mark Levinson and Krell electronics.

I decided to put the nxV500's head to head with the Classe M400's, even though the nxV500 only has 300W/8 which is 100W less than the M400, the sound quality is second to none. Right after hooking them up and pressing play on my reference track of Diana Krall - Live in Paris - Track 1. I Love Being Here With You, it was clear when the bass rolled into the room, it didn't jump or snap into the space like it was a leashed animal, and when Diana's voice is first heard it bloomed beautifully and was sensationally convincing.

The build quality of your product is excellent and it uses high quality capacitors too! I always like to know what the almightly dollar really buys you, and closer inspection of the M400, shows cheap capacitors and internal wiring, including the XLR/RCA interconnect wiring.

In summary the nxV500 is smoother and has greater overall coherence that the hugely expensive mass produced Classe CA-M400 and because of this the M400's have been given the boot and sitting in their place is your very own nxV500 mono blocks!

Thanks again!

Nicholas H Canberra, ACT.

The NXV 500 together with a DAC I have modded and an old Philip CD Player and a Nelson Pass Balanced Bride of Zen delivered the best sound ever in the HIFI club. Sometimes we have some very expensive stereo in the club. 1 month ago only the AR 610 mono amps had a price of $100.000 AUD

So we are extremely satisfied with the nxV500

Cheers from E.Sæterdal



Hi Anthony

I completed my 2ch amp using your NXV200 modules a few months ago, and I must say that the sound quality is absolutely fantastic. Thank you for bringing

this level of quality to an affordable level.

Bartek M, Victoria, Australia

Hello Anthony!

Well I have finished my amplifier using your NXV200 modules. Let me tell you something, I am very picky with sound quality. I have had so many amplifiers that I lost count lol just to name some of them:

Portal Panache, Adcom, Marantz, Bryston, Acurus etc and I have also build many kits including gain clones, chip amps LM3875/LM3886. let me tell you, I am still waiting for the input sonic caps 3.9uf  from Sonic craft. But I could not resist waiting so here I am listening to music. Well let’s start with the quality of your boards, they are top notch, yeah, yeah now you want to know if I like the sound right? Well I have good and bad news....The bad is I lost a lot of time looking for a great amps and amp kits! Ok so what is the good news? I just found you and your wonderful kits! As I mentioned before I had many good amps but, I was never happy with the sound and details. There was always something. well let’s start with these  "small tanks" They are small, I had it for a couples of hours playing with my Polk audio A1 really loud and the heat sink got barely warm. The sound is awesome! I try to listen if I could hear some back noise and I though the amp was unplug so I checked it...but the amp was on! No back noise at all; boy! There is one thing I can say to you............ Very well done! You know me I will get more for sure. Now I only have to wait for these input caps to arrive and I will install them. So far I do not have words to thank you enough for these top notch products.

Your service and products are the best!

Thank you so much Anthony.


Jose Vejar

New York, USA


Hello Anthony,

I compared the nxV300's with my Threshold 450 listening on the Relco Mantis loudspeaker.

In my opinion the nxV300 is more detailed and I will sell the Threshold.


Best regards



Burgdorf, Switzerland

Hi Anthony

After building my new power amp. (HPA-nxV200 modules)

The result is an amplifier, which is, afterabout one week of burn in, able to deliver a very wide soundstage, a powerful, controlled and well articulated low frequency range, smooth and liquid mids and very detailed but never fatiguing highs. But much more important, this amp has a very own but yet very natural sound signature. It really shows me something about my source equipment, but remains playing everything in a very musical manner. I think this is an outstanding product. It has its own signature, not trying to copy any other amp, and it plays just tuneful, full-bodied and convincing. I really searched for some drawbacks here, but wasn't able to find any!

My reference for comparison are some Rotel integrated amps (RA-935, RA-931mkII) and some Naim Audio power amps (NAP 140 and NAP 160). My speakers are some MM Serie Master by Reference 3a, an early version of the current model MM de Capo i.

Thanks for offering such a great product to the diy-oriented!

Kind regards!
Martin Balszuweit

Full comments and photos found in the web site Gallery!

Hi Anthony

 I have been using your amp (nxV200)for over a month now, and have made my decision on its sound quality. It is now my main amplifier and I have sold my Duevel amplifier (I see the new price for these amps is now nearly US $5K)

In my system it gives my speakers a bit more control on bass lines. I listen to a lot of female vocals and the treble is just that bit better suited to my hearing. So you have developed a stunning unit in my view.


All the best


Andy, New Zealand


Hi there Anthony!

..well, the modules (Nxv200) are simply astonishing!

the expected control and resolution on the whole bass region

(sub bass to mid bass) is amazing , especially considered that I use the"old"

psu from my NAD C325B (one toroid, say 230 W ,one integrated rectifier,

two (unknown) 15000 electrolitics) for both the two modules.

even the rest of the spectrum reveals far better resolution,

one of the amazing thinks that I hear is the "life like" sound of metal clash

(in movies effects for example, or cymbals..)

however absolutely non fatiguing sound!

Very well done Mr Anthony E Holton !!!

I'm really a satisfied customer.

Massimiliano Colarusso, Italy


Hi Anthony

I would just like to point out that I think your build quality is far superior to the Classe Audio, I've been doing some A/B testing of the 2 x Classe CA-M400

( http://www.e-hifi.com.au/classe/Amplifiers/cam400.aspx ) and the nxV500's.

I think the nxV500 are better, the M400's are $10.9k each!

You have made some fine amplifiers :)


Nicholas H

Canberra, ACT

Having upgraded my speakers I was looking for something a little better then my monobloc chip-amps, but wanted to keep the chassis as there a good fit with the rest of my system.

So using 45V rails and 20,000uf per unit, in went the HPA-nxV200 modules.The first thing that struck me was the improvment in the bass, very quick and tight.The treble was smooth and detailed, and the resolution just outstanding!

I'm very happy with the results.



Mark G.

Melbourne, Australia

I have a pair of stereo amplifiers using your 4X  NXv200 modules which were assembled by Mark Houston. I have to say that they are the best amps I ever heard.
With experience from a few other amplifiers, yours simply decimate all others. Clarity, soundstage, transparency and speed of bass simply eclipses any other amp that ive heard. They are so crystal clear that they do great justice to my 2 way floorstanders using Scanspeak 18W8531G00 and Vifa tweeter.
The amp is dead quiet. I had to strain myself to hear the slightest stirring of noise but it was coming from my hair that was rubbing against the cone of the speaker! I have thrown all my passive components away and set up my active crossover, with each driver independently powered by your modules.
The sound is so natural and filled with emotion that I challenge anyone to feel nothing after listening to them.
A truly exceptional module you have designed.

Guitar string resonances reveberate with authority! Walls are vibrating though the sub is off. So far this kills my Marantz amp in all aspects; warmth,clarity,soundstage,coherence and speed.
The slightly bright nature of the amp is neutralized by the mellow sounding Vifa tweeter. What emerges is absolute listening pleasure!

Dinesh, Melbourne, Australia

Congratulations on very fine amplifier Anthony, it exceeded my expectations. You should be very proud of this design.

The grip it has controlling a speaker is quite remarkable and smoothness is outstanding. 4 hours straight, no bleeding ears, fatigue or head ache.

Full review found in Gallery section, a must read !

Peter from RZaudio (aka rabbitz) . NSW, Australia

Preliminary listening impressions - no background hum or buzz, very quiet. Amps sound extremely nice! Nice clarity and soundstage, bass is quick and tight.... my goodness. I would say after about 6 to 8 hrs of play time, the sound really came into its own. The bass improved significantly, sound stage is staggering, highs are sweet and the mids are right where I want them. Listening to this amp play was pure pleasure. I am really looking forward to more "seat time". You really are able to pick out subtleties on a CD that you have not heard before - even with my modest system.

Dan Dearlow, Edmonton Alberta, Canada

Wow. Everything was there. Crystal highs, space, tight and deep bass. Everything was so nice balanced, no matter what type of music we were listening. After few hours and a few beers, my brother almost started to cry when we were listening Peter Gabriel's first album

Danko, Israel

Anthony made a Stereo HPA nxV200 Amplifier for me , the improvement over the Arcom AVR300 is mind blowing More detail and bass control in movies [war of the worlds] .

Jeff William SA, Australia

HPA-nxV500 Modules

This is super sound. I am so happy…:-), Huge detail. In the whole audio spectrum, tight and controlled bass, The middle range is so forward and clean without any harshness, No harshness in the top end, Super high end sound. Perfect for me. A little about myself I am 39 years old. I have been interested in HIFI since I was 12 -13 Years old. And I have heard so many amplifiers in my time.

Thank you very much for good product…

Kind regards

Torben, Denmark

HPA-LSP400se Amplifier Review from TNT-Audio.com

HPA-nxV200 Amplifier Listening Impressions & Review

HPA-nxV200 Amplifier Review on DIYaudioprojects.com

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