COLIN WONFOR: HB100 mono power amps test review

Neil McCauley / editor in chief

Why no images?

Because the test review that follows here are of a pre-production pair in casework that doesn't properly represent the finished product which, so we are told, should be available in early March 2017. Priced, including VAT @ £4.6k per pair.

A bit of history

Please note that this introductory text has been shamelessly lifted by me from my introduction to a previous EWA review which you can read at

There’s an old saying that you can judge a person by the company they keep. It’s a truism and a cliché but that doesn’t mean it’s incorrect.

Applied to the hi-fi industry, you can make a reasonable stab at the true nature (behind the carefully crafted façade) of the maker by the claims they make, or if you prefer, the things they don’t say. It’s transparent evidence of a refusal to ‘play the game’ - simply because they don’t feel the need to do so. That’s EWA – in a nutshell.

EWA are Mr. Alan Elsdon and Mr. Colin Wonfor who, between them, have decades of success in the industry. Both are truly grounded in science and design engineering and not media-manipulation. In a hype-ridden industry, this is a rarity; rather eccentric in fact and yes, I like this approach. I explain why, below.

A clean review process

EWA make no outrageous claims regarding any of their products. In fact, they don’t make any claims at all. It’s a refreshing change. So the following review was not influenced - as is so often the case in this industry - on trying to either substantiate or ridicule claims made by the maker.

This means the review process is entirely clean i.e. the product stands or falls on its own merits.

That said, after this review was written I asked HP to invite the two designers for a Q&A session specifically about the HB100. As is usual though, the conversation did wander off-path a bit and then returned.

You can read the full Q&A session at

The HB100 mono power amps

With this, their latest design they have (as I understand it) set themselves the task of achieving simultaneously both extremely low distortion and exceptional output stability. What they have achieved sonically is in my view one of the two most engaging solid-state amplifiers I've yet heard under £10k+

I’m certain that the HB series represents a true beginning of a new family of EWA designs rather than any final statement by them.

These mono amplifiers are rated at 100 RMS per side and probably close to double that into 4 ohms. They sound less like a solid-state design than any others I have auditioned other than the LFD Audio Anniversary series; these being more than double the price.

Note though that I don’t mean to imply or suggest that this latest EWA design cannot be improved upon because - of course they can be – so they say. Their responses to the aforementioned Q&A bears this out.

For me (and other listeners too; why rely just on my opinion I reasoned) listening via these was a revelation in terms of how musical an intelligently designed solid-state power amp mono pair can sound.

Part of their ‘charm’ is their astounding ability to reach the dynamic contrasts of the best program material, and without any sense of strain.

Listening part #1

For the first part of the review session I used three different vinyl pressings of The Who’s Who's Next and then the ultra rare Mobile Fidelity gold CD issue of the same music.

For nerds like me you might be interested to note that, I used:

  • The original west coast Decca pressing because it uses the original master.
  • An early eighties US MCA (cloud label)
  • The Classic Records 200g reissue.

First thing to note is that there are variations in the mixing and mastering over the years that are readily apparent – if you know what to listen for – on even modest audio systems. In the context of this review though, such matters are a bloody nuisance. So why did I do this - bearing in mind I don't get paid for any of this?

What I wanted to determine was to what extent the dynamics and tonal characteristics varied between the pressings via the HB100 design.

Easier said than done but suffice to say that the differences between the three (notwithstanding my best efforts to exclude the aforementioned remastering and mixing changes) were readily apparent through a range of different speaker designs and more so than I have ever previously encountered.

Please don’t take this to mean that these power amps are over-analytical to the point of disassembling the performance into their myriad component parts. This is very far from the case. Yes, I knew even before I wrote the next bit that  – to some – this is a question of semantics but for me the reality is that it was not over-analytical but it was appropriately analytical.

This is all words of course and the proof, should you want to seek it, is that during a demonstration I suggest you take up to three different pressings of the same recording (anything will do, not just The Who) and explore this for yourself. A word of caution though in that I discovered that each of the three Who’s Next pressings presented subtly inconsistent volume levels.

So I suggest you do what I do, preferably with a preamp with a digital read-out of volume and with a sound pressure meter (an invaluable tool in this and many other audition situations) you set the volume control – per recording – so that all are being experienced at the identical sound pressure level. Okay, so far – so good.

Oops. I nearly forgot. what about the MF gold CD? In a word - astonishing. No wonder it commands absurd prices. "Baba O'Riley" at neighbour-unfriendly volumes is a thrill beyond my words to properly describe. You're asking I guess, well .... how did the CD compare to the three vinyl issues? All I can tell you is that it was an entirely different experience in terms of excitement, presentation and many other things too - but there isn't time nor space to go into that right now.

What next?

I am always seeking musical reproduction which is pure and sweet (not to mention quick); qualities that extend down well into the upper mid range. Combine these characteristics with the EWA ‘house sound’ of fast, ambience-drenched low frequency reproduction and it’s a solid foundation for the rest.

Subtract virtually all of those annoying solid-state distortions and you wind up with an amplifier you can listen to for hours on end without getting too homesick for tube units. I can’t express it more plainly than this.

Before switching on and warming up (I left these on for half a day or so, and they run hot so side by side rather than stacked please) I wondered if they would decode surface noise and dirt from my records as well as brightness and grain from my digital collection. It didn’t happen. Knowing previous designs of theirs, I didn’t anticipate that this would occur but ….. well ….. I was delighted that their attention to detail in this respect was as acute as ever.

Listening part #2

I find it all too easy to have my judgment of equipment swayed by the visceral thrill of well recorded rock music. So to achieve some semblance of balance I used other musical genres, both vinyl and digital. These include classical (more on this in a moment) traditional acoustic blues, electric blues, jazz female vocalists such as Linda Hoyle and a lot more besides.

In this context, the details of the artists and my conclusions are of relatively little importance other than to say that by and large, all the performances which hitherto were very engaging became even more so via these amps. Moreover the others which were either poorly recorded and/or poorly remastered albeit with terrific performances (I'm talking bootlegs here) sounded very acceptable indeed.

My preferred classical choice was initially the 1981 recording by Glenn Gould; Bach: The Goldberg Variations. The problem was that candidly I am so mesmerized by the wonder of the piece that I could not focus on what the HB100’s were and were not doing. A case of over-familiarity with that music. So I found it necessary to select a performance / recording less familiar to me.

For convenience, given the range of contrasting pieces contained within it I used the Amadeus original soundtrack vinyl recording.

Even with a few tracks that weren’t entirely to my taste in every instance the sound was thrilling; always in the same emotional direction with only the depth of emotional engagement varying and even then only slightly.

Here are a few of the notes I made. In particular, referring to Serenade In B-Flat for 13 Winds

  • A joy to listen to
  • It touches the gorgeous and most notable music of Mozart
  • Immortal Wolfgang Amadeus Mozart in all his glory. Beautiful!

And so on. You get the idea I’m sure.

A slight but hopefully interesting diversion

Although I use solid-state amplification in my various systems primarily for convenience, overall I have a love and an appreciation of the classic tube sound. What I have noticed in the best of tube electronics is what seems to me their extension of mid range accuracy. In particular, designs from Manley, Radford Revival, EAR/Yoshino and Conrad Johnson. I love them all notwithstanding I hate fiddling about with the damn tubes when required to do so.

What I am about to say is, yes, a generalization but it seems to me that most solid-state units - with a few exceptions – demonstrate a unfortunate trend of going backwards in this respect. In other words the best units have superb reproducing characteristics at the frequency extremes and yet a comparatively unconvincing / un-engaging mid range.

The HB100s seem to be convincing over a greater part of the entire range than most other solid state amplifiers I have heard.

A word about imaging. These units are quite simply one of the two finest reproducers of the front to back depth in solid state and I've yet heard.

The low end has the authority of some of the finest power amps I can yet recall hearing. On first listening the bass appears to be a little lightweight. However it doesn’t even take careful listening to realise what one is hearing is an almost unprecedented level of bass agility and tautness. I came to realise that other solid state favourites of mine are a little too warm; a little too rich giving the impression of greater bass heft and weight.

Dynamics were reproduced without a hint of electrical or mechanical character. From the softest part of acoustic strings to the visceral power rock climax these units describe volume changes effortlessly.

With the room lights turned off I forgot I was hearing an electronic system. At high volumes the sense of composure is stunning, A real power powerhouse without any need to shout about it.

With many otherwise excellent solid-state devices, loudness peaks are accompanied by a flattening of the sound stage and (for me at least) a diminution in perceived image height. I am particularly sensitive to the image height characteristic or is, so often the case, the lack of it. I’m not the only one who has spotted this. Until these power amps I suspected that this has been a great, lingering curse of solid state amplification. I now realise it isn’t a limitation of solid state technology but the implementation of it.

No part of the frequency spectrum called attention to itself.

I just has to try solo acoustic guitar through the system. John Williams was my default choice. The HB100s maintained just the right proportion of fundamental to overtone. Lesser amplifiers either fail to differentiate between strike and decay or worse, they dissect and separate these elements in an intrusively analytical manner. Here though these individual components of sound possess a clear, precise relationship to each other.

A bit more about the acoustic image

Observations and audio criticism of sound-staging and imaging are I find deeply personal – for those that care about this kind of thing. Some of you don't. I know this.

Some listeners, for instance, place emphasis upon the focus of individual images while others might sacrifice that last bit of precision in this area in favour of a larger overall sound stage. I found here that the size and location of the individual voices on the Handel Messiah (Trevor Pinnoch recording) were presented in realistic proportion to one another and that positions were maintained. Similarly with Faure Requiem ( John Rutter recording) and others in a similar vein.


This is an ideal power amplifier pair and it works wonderfully with all and any loudspeakers I tried and provides ample power output to satisfy all my listening tastes.

These units convey the elusive and precious musical quality better than its competitors within the price band and quite possibly multiples thereof. This results in a listening experience which was – for me - fundamentally more lifelike and credible than pretty much anything else.

These units are substantially raising the bar of performance within the price band.

This is an outstanding effort by these two world class gentlemen designers and a true achievement in an industry that too often emphasizes technology over music. Two final words; unhesitatingly recommended.

Please contact me HERE for details on where EWA can be auditioned in the UK.

Thank you. Neil McCauley / Editor in chief

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