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Seeking Cost/Performance Input and Thoughts: Hypex vs Purifi vs Benchmark

March Audio

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This is an interesting question - does one need low-pass filters to reproduce Class D performance when doing actual listening? Or is the ultrasonic noise sufficiently high that it doesn't matter for listening and only impacts broadband (aka up to high ultrasonics) measurements?
The Hypex and Purifi have output filters. This switching signal is at 450 to 500 kHz and what low level signal remains has no impact on your listening or speakers.

Regarding gain don't be concerned at all. You will just turn up your dac or pre 3dB louder. So long as your dac has a high enough output to drive the amp to full output its a non issue. If anything the lower gain will probably have lower noise levels.

There is nothing in the LKV that will justify spending $9k more. In fact with zero feedback in the buffer I would expect that to most likely ruin the excellent performance of the Purifi module.
 
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Paperdragons

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Expanding on a topic that's come up in another thread, I'm looking to buy my "endgame" power amp - something that not only measures well, but also is sufficiently audibly transparent that I can feel confident that I can put it in my system and not have to think about upgrading ever again.

While equipment, life, and living spaces can of course change in the future, long story short is that I'm confident that the power rating of the 400/500 Hypex and Purifi modules (and equivalent Class AB designs) is more than enough for my needs - and I'm happy to pay the small price premium for a Hypex 500-based amp over a 250-based amp even though a 250 probably would be sufficient.

So... I'm trying to decide among the following - and FYI I like the Audiophonics for Class D because I like the build quality, the positive owner reports here, the availability of both RCA and XLR jacks, and the heatsinking, internal airspace, and front-mounted power button of their component-sized HPA cases:
  • Audiophonics HPA-S500NC (2x Hypex 500 with inegrated PSUs) - approx $900USD
  • Audiophonics HPA-S400ET (2x Purifi 400 + 1x Hypex 1200 PSU) - approx $1400USD
  • Benchmark ABH2 - $3,000USD
My main questions, then, are what people's thoughts are on:
  1. The $500 extra for the Purifi unit. On the one hand, it would seem unnecessary if the Hypex-based amp is already audibly transparent. On the other hand, if I'm planning to keep this amp for a decade or longer (basically until it eventually breaks), would it be wiser to go for the better specs to future-proof it against any possible future upgrades of other components that could conceivably reveal a small audible difference between the Hypex and Purifi amps?
  2. Gain considerations: Benchmark vs Class D. The extra $1600 would be a stretch for me, but not a crazy one - I am fortunate enough to be able to afford it, even though I have to carefully weigh the expense. One concern I have about the Class D amps is that they provide about 25-26dB of gain, while my current amp, an Adcom GFA-5400, provides 29dB. I use my Oppo BDP-205 as a digital preamp, and I do have some room to increase its volume to compensate. Am I correct in assuming that the 3-4dB difference in amp gain corresponds to just a small change in the Oppo's (or any preamp's) volume control? Will the Benchmark's high and low gain switch capability be a significant advantage over the Audiophonics in this regard?

Obviously I will need to make my own decision and depend on my own judgment. But I do find others' perspectives really helpful and would appreciate folks weighing in if they want.

Thanks!

Best,
Matt

I haven't personally used any of these amps and I am definitely not an expert. The ABH2 probably fits the use case of 'endgame' better than the audio-phonics options. I tend to caution away from thinking in terms of endgame, though. One thing to consider as well as that amp lifespan can vary quite a lot and it's possible any of these could malfunction at any point. For gear you intend to keep for some time, another factor that isn't often brought up is aesthetic. If you don't like its aesthetic design you probably won't want it around for 15 years or longer.

In terms of price to performance the Audiophonics (hypex) option wins out by default for meeting your spec at 1/3 the price of the competition. The benchmark is unlikely to be 3x better at any aspect of its job let alone overall than the audiophonics. It's going to be more than enough to 'future proof'. Its performance appears more than adequate and I suspect dumping the savings into 'endgame' speakers would have more impact on the quality of your ideal system. I don't think you should be worrying about any of these amps as they all fit your power requirements and are well regarded.

Anyway, I hope you enjoy your new amp :)
 

CDMC

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The first question that pops in my mind is: What don't you like about the Adcom 5400? They were pretty good amps. I think explaining that may help make a better informed decision as which path you choose (of which any of them are excellent choices, so you can't go wrong).
 
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tmtomh

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I haven't personally used any of these amps and I am definitely not an expert. The ABH2 probably fits the use case of 'endgame' better than the audio-phonics options. I tend to caution away from thinking in terms of endgame, though. One thing to consider as well as that amp lifespan can vary quite a lot and it's possible any of these could malfunction at any point. For gear you intend to keep for some time, another factor that isn't often brought up is aesthetic. If you don't like its aesthetic design you probably won't want it around for 15 years or longer.

In terms of price to performance the Audiophonics (hypex) option wins out by default for meeting your spec at 1/3 the price of the competition. The benchmark is unlikely to be 3x better at any aspect of its job let alone overall than the audiophonics. It's going to be more than enough to 'future proof'. Its performance appears more than adequate and I suspect dumping the savings into 'endgame' speakers would have more impact on the quality of your ideal system. I don't think you should be worrying about any of these amps as they all fit your power requirements and are well regarded.

Anyway, I hope you enjoy your new amp :)

Very wise - thanks! And thank you @March Audio for the filter info - much appreciated.
 

tomelex

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The first question that pops in my mind is: What don't you like about the Adcom 5400? They were pretty good amps. I think explaining that may help make a better informed decision as which path you choose (of which any of them are excellent choices, so you can't go wrong).


Yes, this is the question from a logical rationale, but I think part of this is just plain old audiophile wanting to upgrade because its fun, I could be wrong, but you do ask the real question, I have often asked folks, just what is it that your current system is doing wrong, then once there is a viable answer to that, only then think about "upgrading", unless you just want a new toy, then get a new toy. We all like a new toy once in awhile, well, except maybe me, have stuff that has been running for over three decades now. But, (stroking his chin) that new XYZ sure looks cool. :)
 

SIY

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LKV has given me an interesting product idea. Take a good amp module with low gain (the Purifi or Orchard come to mind) and couple that with an actual high performance tube input stage. I may lose a zero or two on the THD, but still be a few orders of magnitude below audibility (say, 0.002-0.003%). Where I'll need help is making up a story to go with it.
 
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tmtomh

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The first question that pops in my mind is: What don't you like about the Adcom 5400? They were pretty good amps. I think explaining that may help make a better informed decision as which path you choose (of which any of them are excellent choices, so you can't go wrong).

You raise an excellent question, and I agree with @tomelex 's main points. In my case, there's nothing that I don't like about my Adcom GFA-5400 - it's an excellent amp, it's given me great joy for years, and if someone told me I had to live with it forever, I wouldn't be especially unhappy. In fact, it's only the 2nd power amp I've ever owned, and the 1st one was a Nelson Pass-designed Adcom unit as well (a GFA-535). I got the 5400 about five years ago, used, for $190 ($150 for the amp off eBay, and $40 to my tech to look it over to make sure it was operating to spec and didn't need any components replaced). I got it mainly because I'd always liked the 535 (which I'd had for about 20 years at the time), and the 5400 has double the power reserves and was in the same "family tree." Plus it was incredibly cheap and from the earlier, Japan-made run of this model (no offense to the Chinese-made units, but Chinese manufacturing 25-30 years ago was not necessarily as reilable or refined as it has been for the past decade or so).

I guess I'm looking to upgrade for two main reasons:
  1. The Adcom has served me well but it has zero speaker protection circuitry, and so if it were to fail catastrophically one day, it could take one or both of my speakers with it.
  2. I got into Pass-designed Adcoms in my early 20s, based on reviews in the audiophile magazines. The 5400 has relatively high distortion specs (I think 0.18%?) and while it's not one of the more extreme Pass designs with no feedback, I've drifted away from having full confidence in his design philosophy since I've become familiar with sites like this over the last few years. While I admit I have no proof that the 5400 is not audibly transparent in my listening room at normal listening volume, I sort of suspect that one of the amps I'm considering might sound a little different than the 5400 because it will lack some distortion or coloration or "voicing" that Pass might have baked into the 5400's design based on his own philosophy and/or preferences.

As for wanting a new toy, I would no doubt experience an initial rush of enjoyment from the newness of a new amp - but honestly, a power amp is not my idea of sexy, and the idea of looking at my power amp while I listen to music is not at all exciting to me. I just want a nondescript-looking black box that will amplify the signal and otherwise get out of the way entirely (which is why I'd have zero interest in something like the LKV even if it were 1/5 the price). I'd like to feel that when I listen to my music, all the "voicing" comes from the recording/production itself, and (unavoidably) the speakers. I don't want to hear the sound of my amp, and I'm not fully confident that that's the case with my current unit.
 
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Eurasian

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I think Peter Aczel had it right many years ago when he suggested that power amplifiers had the easiest job in the hi-fi chain, and that competently designed amplifiers operated under clipping are virtually indistinguishable. Having said that, if you can afford them, in my opinion you should go for the Benchmarks.
 

Voo

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I dont think I will ever understand the idea that amps will usually sound the same. every amp I have owned over last 30 yrs sounds different...even avr's...I dont bench test them, but use them in rooms hooked up to speakers. ofc, this is measurement based I suppose...so just buy best measurement based amp. I remember a very old adcom 5803 amp...it sounded like crap back in day....20 yrs ago...I returned it quick.
 

SIY

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I dont think I will ever understand the idea that amps will usually sound the same.

They won't if one of them is clipping. Or if you do the evaluation without level-matching and preventing peeking (ears-only). Amazing how if amps are run within their limits and you have to just rely on your ears those differences seem to vanish...
 
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tmtomh

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I dont think I will ever understand the idea that amps will usually sound the same. every amp I have owned over last 30 yrs sounds different...even avr's...I dont bench test them, but use them in rooms hooked up to speakers. ofc, this is measurement based I suppose...so just buy best measurement based amp. I remember a very old adcom 5803 amp...it sounded like crap back in day....20 yrs ago...I returned it quick.

Interesting. My father has an Adcom 5802 powering enormous Infinity Kappa 9's. I'm not a fan of any amp with a fan in it, but otherwise that 5802 is a total beast and sounds just fine to me.
 
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tmtomh

tmtomh

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Goodness - I completely forgot to mention one other, major reason I'm looking to move on from the Adcom: it produces low-level white noise from my speakers. Fortunately I have to get within about a foot of a speaker to hear it - but I'd rather have an amp that is silent or closer to it.

I guess at some level I don't get the point in the long-term of having a source component like my Oppo UDP-205 upstream from an amp whose noise performance and distortion specs can't fully match it.
 

digitalfrost

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I think it's a false comparison to put the cheapest available NC500/Purify amps against the Benchmark. If you would buy such an amp from a similar company, like an NAD M22 V2 or M32, the price would be similar or higher than the AHB2.

Of course for your choice in the end it doesn't matter when all you care about is price/performance from an amplification perspective. That said, you don't have ASR measurements for these amps, and you have to hope/trust they didn't degrade what the modules offer.
Anyway it's a bit of an apples to organes comparison because these cheap amps don't come with custom built cases, the HPA-S400ET doesn't have 12V trigger, AHB2 offers gain adjustment at the back of the amp, S400ET seems to need the top cover removed to access the jumpers...

What I'm trying to say is. Besides SINAD and power, these are not the same product. If that matters to you is another question.
 

Voo

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They won't if one of them is clipping. Or if you do the evaluation without level-matching and preventing peeking (ears-only). Amazing how if amps are run within their limits and you have to just rely on your ears those differences seem to vanish...
well when I compare stuff its usually at close to max performance....so yea...if something clips, I dont care for it vs something that doesnt clip.
 

Xulonn

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I don't think I will ever understand the idea that amps will usually sound the same.

Based on your subsequent comments, and apparent unfamiliarity with the words "limits" and conditions", you likely will never understand - and now we know why... :rolleyes:
 

Eurasian

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Low amplifier output impedance is important, too, along with reasonable cables — read low capacitance and resistance/moderate inductance.
 

tomelex

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I dont think I will ever understand the idea that amps will usually sound the same. every amp I have owned over last 30 yrs sounds different...even avr's...I dont bench test them, but use them in rooms hooked up to speakers. ofc, this is measurement based I suppose...so just buy best measurement based amp. I remember a very old adcom 5803 amp...it sounded like crap back in day....20 yrs ago...I returned it quick.


Well, they (amps) do and they don't. So, testing on a resistor load is not the same as testing against a speaker load. Comparing two feedback solid state amps operating in class AB with similar specs will generally sound pretty much the same. But, now test an OTL tube amp against them, or a class A solid state amp of the same general specs: with or without feedback, or an amp with adjustable feedback, and you could very well hear differences. IF you listen to similar topography of circuits with nearly the same specs then it is damn hard or impossible to hear a difference if they are operated well within their ratings. Young ears are better at hearing these differences than old ears like Michael Fraemers (spelling). Amps output impedance and they way they handle the reactive load are measurable differences.
 
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CDMC

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Interesting. My father has an Adcom 5802 powering enormous Infinity Kappa 9's. I'm not a fan of any amp with a fan in it, but otherwise that 5802 is a total beast and sounds just fine to me.

It's a 5800 then. The 5802 got rid of the fan.
 

CDMC

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I think at the end of the day, you have to decide first if you want to stick with Class A/AB or go to Class D. There is no doubt that Class D is the way of the future, clean, energy efficient, and little heat. I purchased my first Class D amp recently and am happy with it, finding that it has a bit more clarity and sounds less grainy than the small Class AB amp it replaced. Whether it is the old amp wasn't working right, it in fact sounds better, or I am imagining the improved sound is a matter for debate.

If it were me, I would go the Purifi 400 route. It gets you more power than the Benchmark (225 watts/ch 8 ohms, 425 watts/ch 4 ohms) which will likely comfortably drive any speakers you purchase. It also gets you the latest in Class D technology. Finally, if you think you might get upgraditous down the road, you could purchase from Nord and have the ability to play with different input buffers.

One thing to keep in mind is that even high end manufactures are purchasing Class D modules and then throwing them in their own case with their own custom buffer stage and charging a fortune. You can get the same amp for less. Also, I am not impressed with the idea of spending $10,000 for a zero feedback front end. Both Hypex and Purifi use a great deal of feedback. As their designer says, feedback is not bad, it is bad implementation of feedback that is bad.

If you haven't watched it, I strongly suggest watching Buron Putzeys speech at Burning Amp in 2012. Ironically, the audio quality is horrible, but he discusses a lot of why he did what he did in designing the Hypex amps.

 
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