[WGH]

I would think if the distortion is below a threshold in both amps they would sound the same.

That is what Julian Hirsch, founder of Hirsch-Houck Laboratories thought. Hirsch estimated that he wrote about 4,000 laboratory test reports for various publications, 2,400 of those at Stereo Review from 1960-1998. Julian Hirsch retired as Stereo Review's Editor at Large.

[goryu]

I am hoping someone will post good resources to read about the difference between a traditional audio power amp and the new digital type amps. I would think if the distortion is below a threshold in both amps they would sound the same. I guess not.

Google is your friend.

There is more going on that just simple distortion. Music is a complex waveform, not a single frequency test tone. There is the interaction between the speaker, whose impedance is constantly changing with changing frequency, and the amp. Not all amps have the same distortion with output power- it varies differently and in different amounts with different output power levels. There are many factors at play that can account for slight differences, whether those differences are each individually, or in sum, audible, is another matter. There have been many tests done where test subjects could not tell the difference between amps in blind testing.

[AllanS]

Google is your friend.

There is more going on that just simple distortion. Music is a complex waveform, not a single frequency test tone. There is the interaction between the speaker, whose impedance is constantly changing with changing frequency, and the amp. Not all amps have the same distortion with output power- it varies differently and in different amounts with different output power levels. There are many factors at play that can account for slight differences, whether those differences are each individually, or in sum, audible, is another matter. There have been many tests done where test subjects could not tell the difference between amps in blind testing.

https://www.passlabs.com/technical_article/audio-distortion-and-feedback/

https://benchmarkmedia.com/blogs/application_notes/131919495-ahb2-crossover-distortion-measurements?_pos=6&_sid=3bfa23744&_ss=r

I’ve spent some trying to understand differences and agree that Google is your friend as are a lot of threads here and other places.  What I gleaned from those the threads is mainly that well implemented can sound really good to some and crap to others regardless of amp class.  Poorly implemented is just poorly implemented.  And everything has to do with personal preferences and what aspects of sound quality you value.
That said I learned a lot from tech articles from the likes of Nelson Pass and Benchmark.  There you can find basic information that provides insight into what and why different folks go about things in different ways but there aren’t any places that I found that are going to give you the guidance I think you’re looking for.  Good luck.

[goryu]

What I gleaned from those the threads is mainly that well implemented can sound really good to some and crap to others regardless of amp class.  Poorly implemented is just poorly implemented.  And everything has to do with personal preferences and what aspects of sound quality you value.

As I have been saying...

[Letitroll98]

This all seems to be far away from NCore vs Purifi.

[goryu]

This all seems to be far away from NCore vs Purifi.

If you wish to compare two amps designed by the same engineer, with nearly identical measured performance, cost, etc., why wouldn't discussions relating to perceptions, audibility limits, the role personal preferences play, etc., be entirely relevant?

[Letitroll98]

If you wish to compare two amps designed by the same engineer, with nearly identical measured performance, cost, etc., why wouldn't discussions relating to perceptions, audibility limits, the role personal preferences play, etc., be entirely relevant?

How did I know you'd disagree. 

[Early B.]

How did I know you'd disagree.

For those who aren't aware -- NCore and Purifi are designed by the same folks (led by Bruno Putzeys). If you want a technical explanation of measured performance and why those amps sound differently, there are several YouTube videos where Bruno discusses this topic. 

[nc42acc]

No way they can sound different. Please post links to this video.

For those who aren't aware -- NCore and Purifi are designed by the same folks (led by Bruno Putzeys). If you want a technical explanation of measured performance and why those amps sound differently, there are several YouTube videos where Bruno discusses this topic.

[Early B.]

No way they can sound different. Please post links to this video.

I assume you know how to search in YouTube. If not, ask someone to show you. 

[nc42acc]

Wow! You posted making claims about the differences in the amps but get defensive and belligerent went asked to produce what you claim. Nice.

I assume you know how to search in YouTube. If not, ask someone to show you.

[Early B.]

Wow! You posted making claims about the differences in the amps but get defensive and belligerent went asked to produce what you claim. Nice.

You falsely claimed that I made claims, but produced no evidence. I've never heard an Ncore amp, so I'm in no position to post on the differences. I personally don't care about the differences. I'm just trying to help out folks who want to learn more about the two amps from the guy who designed them.   
   

[nc42acc]

Oood try at deflecting the source of this interaction. Here is what you posted.

“If you want a technical explanation of measured performance and why those amps sound differently, there are several YouTube videos where Bruno discusses this topic.”

All I asked is your provide links to these said videos as I assumed you had watched them. You told me I was basically too stupid to search and find these said videos with outside assistance. I did search and did NOT find anything with Bruno discussing this or saying why or if they sound different.

Please provide links to the videos you posted about.

You falsely claimed that I made claims, but produced no evidence. I've never heard an Ncore amp, so I'm in no position to post on the differences. I personally don't care about the differences. I'm just trying to help out folks who want to learn more about the two amps from the guy who designed them.   
 

[nc42acc]

Here is a chart for reference. How can all these Hypex and Purifi based amps with such high SINAD have different sonic signatures? It is not electrically or scientifically possible.

[Early B.]

You told me I was basically too stupid...

You did it again. I never said you were basically too stupid to search YouTube. I don't know you and even if I did, I wouldn't call you or anyone, "stupid." I'm smart enough to use a more colorful description.  

[nc42acc]

Still no YouTube links. Read what you posted below as directed to yourself from a fellow member.

I assume you know how to search in YouTube. If not, ask someone to show you.

[nc42acc]

Does anyone else have knowledge of these elusive YouTube videos that show Bruno Putzeys explaining the difference between the Ncore and Purifi modules and how they “sound” differently?

[goryu]

Does anyone else have knowledge of these elusive YouTube videos that show Bruno Putzeys explaining the difference between the Ncore and Purifi modules and how they “sound” differently?

If you check into the different amp sellers, you will note that each reseller offers different input buffer options and corresponding different op amps in the input buffer. These different buffers/op amps have different sonic signatures and thus the amps can be "tuned" by the buyer's choice of input buffer/op amps to produce a sound signature to suit the buyer: some are warm, some more neutral, etc. This is how different commercial Hypex and Purifi based amps can sound differently.

[WGH]

The Nord One NC500DM MKII Dual Mono Stereo Amp is an example
https://www.nordacoustics.co.uk/product-page/nord-one-nc500dm-mkii-dual-mono-stereo-amp



2 x Hypex NCore NC500 Module

Hypex designed the NCore NC500 with a separate input section to allow manufactures to add their own house sound via the input buffer section.

We went one step further by designing a board with the ability for you to change the sound of the amp using different Operational Amplifiers or Op Amps via an on board socket, we call it Op Amp rolling.

Using Nord REV D Input Buffer Boards with high-end discrete Sparkos Labs Voltage Regulators and a choice of Sparkos Labs SS2590 or the Sonic Imagery 990Enh discrete Op-Amps, both run in full Class A. And offers a richer, warmer, tonally dense musical sound with greater soundstage.

£1,379.00

[goryu]

There you go....