Audiophonics HPA-S400ET Review (Stereo Amplifier)

[nemesis.ie]

I'd be interested if it had an XLR AES input.

 

[Rolka]

Hi all, I registered to this fantastic forum, because I'm interested in this amp, but after reading a lot about this one and other Eigentakt amps like the NAD 298, I'm super confused by a few things. And i worry a bit regarding sound aesthetics or what some people perceive as such, compared to a clinical sound and what change I could expect from making the switch. I have a 30 year old NAD 208 amp which is driving custom built Dynaudio 2-way speakers at 2 ohm (about 750W per channel). Back in the days I tried many amps and I honestly have no idea how much the speakers actually need to become dynamic and a joy to listen to, but back then this amp was my fav. And though I'm an electronic musician and sound designer, I've never wanted to actually exchange this compo for active speakers, because I like to listen to the sound much more than the clinical sounding monitor speakers I got to know over years, except for some very expensive ones.
When I read that these Eigentakt amps sound "neutral", I get a bit concerned that I might get listening exhaustion quickly due to absence of some "good" distortion that my NAD produces and also transients that might become too harsh in some cases?
I don't know if these concerns are justified, but related to them and the negation in this forum that changing the op-amps has a positive effect on the sound, I'm wondering if that is also true from an aesthetic perspective? And is their main purpose the coloration of the sound at all or more of a correctional stage, but due to the clean signal it's neglect able? Is it something that you'd say is so minimal that I shouldn't get concerned or is there some truth to changing them and also others things like binding posts etc? I'll quote from one customer of the discussed amp who wrote a review on the audiophonics page:

Toshiki K.
Rather good, but needs modification
The positive binding post of R Ch is unfavorably connected to GND due to the phase inversion at R Ch for reducing bus pumping. This is because negative output of 1ET400A is connected to GND internally.
Sound quality is not good enough for me, though is better than that of Hypex NC400 with SMPS600N400. I replaced the interface card with Purifi FE02 front-end board, in which OPA1612AID OPamps and low noise discrete regulators are incorporated. They seem to have higher performance than LM4562NA OPamps and conventional 3-terminal 7815 and 7915 regulators used in the interface card. I also changed cables connecting output Faston-tabs and binding posts to Cardas CROSSLINK 1S speaker cables that have star-quad configuration. The sound quality has come to be worth 5 stars.
I hear that FE02 is not permitted to be incorporated in commercial products by Purifi. Sound quality would be better if discrete 3-terminal regulators were used instead of the IC regulators in the interface card, because some sound degradation probably originates from noise and inadequate transient response of the regulators. The reason for reduction of 2 stars here is that modification is necessary for excellent sound.
Apart from the product, I felt kindness and faithfulness in customer service personnel.

What do you think about such modifications? Are they worth it, i.e. have you personally ever heard that such upgrades make a big difference in the sound? Does it come from added harmonics or a change in transients/dynamics? And would you say these differences are an increase in sound quality or rather a matter of taste?

 

[Cadguy]

Yesterday I noticed by chance that the amp emits a relatively low-level, but still audible (when putting my ear right next to the amp) high-pitched "whining" noise when switched off. When I turn the amp on, this noise stops and is replaced by a lower-frequency noise, again not very high in level. Nothing major, but I was wondering what's going on there and if there is any way to get rid of it altogether?

May I ask how close to the amp your ears have to be to hear the whine? Can you hear it when your ears are 2 feet away?

 

[AlexDD]

Is it possible to use this amp for a 2.1 system?

 

[nemesis.ie]

@AlexDD As long as your source can output a separate sub connection or your sub has high-level inputs/outputs, yes.

 

[Satyadhara]

May I ask how close to the amp your ears have to be to hear the whine? Can you hear it when your ears are 2 feet away?

No, I have to get much closer to the amp, like 20cm or so. I wrote to Audiophonics (just out of interest), and this is the reply I got:

Hello,

all Stand-By power supply make noise.
this is inherent in its operation.
I invite you to do the same thing on all products using a stand BY power supply (Internet box etc...)
unfortunately it is not possible to remove this noise
best regards

 

[nemesis.ie]

Actually it is possible, you put in a triggered mains switch. Audiophonics even sells one.

 

[Axel Endriss]

Is it benefical to use a RCA-2-XLR cable to connect between Preamp (RCA output) and the HPA-S400ET (XLR input)? Or is it that what one puts in is what one gets out, independent of which input (at the HPA-S400ET) is used?
I do not expect any audible difference, but perhaps a difference in volume due to different sensitive inputs.

 

[Axel Endriss]

Yesterday I noticed by chance that the amp emits a relatively low-level, but still audible (when putting my ear right next to the amp) high-pitched "whining" noise when switched off. When I turn the amp on, this noise stops and is replaced by a lower-frequency noise, again not very high in level. Nothing major, but I was wondering what's going on there and if there is any way to get rid of it altogether?

Mine is silent as a brick if switched off. But when it's switched on I can hear some hum. It's not loud at all and most people perhaps do not hear or at least would not be bordered, however, I can hear it even on 3 m distance. It sounds like a refrigerator humming somewhere in the distance. You don't really hear it, but when someone unplugs it, you can hear that you can't hear it anymore.

 

[Axel Endriss]

Hi all, I registered to this fantastic forum, because I'm interested in this amp, but after reading a lot about this one and other Eigentakt amps like the NAD 298, I'm super confused by a few things. And i worry a bit regarding sound aesthetics or what some people perceive as such, compared to a clinical sound and what change I could expect from making the switch. I have a 30 year old NAD 208 amp which is driving custom built Dynaudio 2-way speakers at 2 ohm (about 750W per channel). Back in the days I tried many amps and I honestly have no idea how much the speakers actually need to become dynamic and a joy to listen to, but back then this amp was my fav. And though I'm an electronic musician and sound designer, I've never wanted to actually exchange this compo for active speakers, because I like to listen to the sound much more than the clinical sounding monitor speakers I got to know over years, except for some very expensive ones.
When I read that these Eigentakt amps sound "neutral", I get a bit concerned that I might get listening exhaustion quickly due to absence of some "good" distortion that my NAD produces and also transients that might become too harsh in some cases?
I don't know if these concerns are justified, but related to them and the negation in this forum that changing the op-amps has a positive effect on the sound, I'm wondering if that is also true from an aesthetic perspective? And is their main purpose the coloration of the sound at all or more of a correctional stage, but due to the clean signal it's neglect able? Is it something that you'd say is so minimal that I shouldn't get concerned or is there some truth to changing them and also others things like binding posts etc? I'll quote from one customer of the discussed amp who wrote a review on the audiophonics page:

What do you think about such modifications? Are they worth it, i.e. have you personally ever heard that such upgrades make a big difference in the sound? Does it come from added harmonics or a change in transients/dynamics? And would you say these differences are an increase in sound quality or rather a matter of taste?

Perhaps helpful to you: I replaced my about 30 years old Linn LK1 power amp by Allo's Volt+D. I bought it for my stereo in the basement where I run an Allo Boss Player. The idea was not to replace my LK1 in my main system, but I tried it there also even so I didn't expected an improvement. However, the sound improved so much that I haven't connected the LK1 anymore. By this I mean that I could hear details which I've never heard on songs which I've listend many times. This mostly applied for good quality recordings. Later on I bought the HPA-S400ET just because it got good raitings and I thought I might be surprised another time. And in fact this happend again. Concerning "clinical sound" I'm wondering what people mean about it. If it's that the signal at the output does not sound better than what has been entered to the input I do confirm that the HPA-S400ET makes this very transparent. I.e. I do hear more differences between different recordings and the effect is black and white. So I do recommend to give the HPA-S400ET a try.

 

[JoetheLion]

No, I have to get much closer to the amp, like 20cm or so. I wrote to Audiophonics (just out of interest), and this is the reply I got:

Hello,

all Stand-By power supply make noise.
this is inherent in its operation.
I invite you to do the same thing on all products using a stand BY power supply (Internet box etc...)
unfortunately it is not possible to remove this noise
best regards

NAD told me more or less the same thing about my C 298.

 

[AlexDD]

@AlexDD As long as your source can output a separate sub connection or your sub has high-level inputs/outputs, yes.

What are high-level inputs/outputs?

 

[Caliban]

What are high-level inputs/outputs?

That would be inputs on the sub intended for connection to the amplifier speaker outputs.
There can also be high level bypass connections on the sub which then would be considered outputs.
Be aware though, read the sub / amp documentation first. Some subs connect the L/R negative poles
together in their high level inputs and some amplifiers do not like that. Check what applies to your system.

 

[Ev(tired of the hype)G]

You get what you pay for. It is not a bad deal In the USA but EU residents definitely have better options. Anyone who has a screwdriver, wire strippers and pliers, a little heat shrink tubing and insulated tape can address most of the VTV shortcomings with little effort unless if there is a flaw in the buffer board manufacturing. I think Most here are choosing the Eval1 version anyway.

it is nice to have several different options from different assemblers and the consumer can choose vote with his pocketbook. It’s nice that audiophonics can put some price pressure on its competitors in the EU. For those based in the USA I wouldn’t scoff at VTV if you are handy with a soldering iron. It’ll be nice when Buckeyeamp has It’s Purifi amps in production. I’m eagerly awaiting a measurement on a new Purifi 1ET7040SA which appears only have beefier thermals for people who want to blast power through low impedance speakers but minimal benefit over the 1ET400A for most users.

On 11/30/22– it cost me $1430 total out if pocket, shipped to me in California:,arrived in four days. Faster than I received an audio article from Texas. Exchange rate was offset by Paypal‘s exchange rate cut.

 

[Acerun]

Thanks, @amirm. Excellent price/performance ratio, for sure!

But we unsurprisingly get what is expected performance from a close-to-reference design : 1ET400A + SMPS1200 + transparent buffer board (which is good). Minor differences are due to either production variation or Gain settings. Personally, I would spend a bit more for BoXem Arthur 4215 (for form factor, auto off/on and overall build quality) but none would "sound" any better than the other.

For those who don't know, there's also a cheaper version, with the exact same components in a smaller case:View attachment 194315View attachment 194320

AUDIOPHONICS LPA-S400ET Class D Stereo Amplifier Purifi 2x400W 4 Ohm - Audiophonics

We are proud to offer you the Audiophonics LPA-S400ET, a Class D stereo power amplifier based on two Purifi 1ET400A modules. This ready-built and ready-to-use version is for audiophiles who want to equip themselves with a foolproof amplification

www.audiophonics.fr

The Boxon you listed has no RCA in

 

[Acerun]

On 11/30/22– it cost me $1430 total out if pocket, shipped to me in California:,arrived in four days. Faster than I received an audio article from Texas. Exchange rate was offset by Paypal‘s exchange rate cut.

$1360 today delivered to California

 

[Acerun]

Benchmark AHB2 has been out since 2014 and still hasn’t been bettered in many aspects of measured performance. Looking forward to someone knocking them off their perch!

Didn't the PA5 knock it off?

 

[Billy Budapest]

Didn't the PA5 knock it off?

No, the PA5 did not. The Topping LA90 did, but my post you quoted above was from before the LA90 was released.

 

[Acerun]

Can someone tell me what the maximum output voltage is for this unit? I have a Denon x3700H and I believe Amir recommends external amplifiers that output under 1.4 volts.

 

[Scetes]

Hi there. I'm new to the forum. Apologies if I'm posting this in the wrong thread. So glad to see objective evaluations of audio equipment. I'm not an EE, so this is a basic question. My speakers (Polk R700, 87db sensitivity) are rated for 50-300W. This Audiophonics HPA S400ET can put out 400W per channel. I'm up for trying one of these highly rated Class D amps. Question - is this S400 too much power for my speakers? If yes, any suggestions for a lower powered but high scoring Purifi or Hypex amp? BTW, I'm not interested in DIY. I currently have a 100W per channel amp (Schiit Vidar), have a small (13x15 ft) room, and listen at low to med levels. In other words, I'm interested in better sound, and not wanting for higher decibel listening level. Oh, and I have a Benchmark DAC2 L that I use as preamp, if that matters. Thanks for any help.