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A more appropriate way to state the question would be to ask what assumptions are behind this statement.

The idea is that an amp should not change the signal other than to amplify it. An ideal amp should not introduce any distortion and should be able to amplify all frequencies identically without being affected by the load.

The problem with the statement is that there is no perfect amp. The point at which you decide that performance is adequate and differences are irrelevant is a very subjective decision and based largely upon one's perspective.

There are lots of amps that many would assume to be well designed and adequate, and may or may not sound the same. This is a matter of debate and you have opened a proverbial "can of worms."
 

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Essentially, there are a variety of measurements that correlate directly with perception (there is an entire field of science dedicated to this). With modern technology it is no longer a challenge to design and build a unit that far exceeds these thresholds for audibility such that all amplifiers, if properly designed and working within their specified parameters*, will amplify a signal with no audible coloration.

*This assumes the amplifier is not broken, or is not being pushed to clipping etc...
 

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Essentially, there are a variety of measurements that correlate directly with perception (there is an entire field of science dedicated to this). With modern technology it is no longer a challenge to design and build a unit that far exceeds these thresholds for audibility such that all amplifiers, if properly designed and working within their specified parameters*, will amplify a signal with no audible coloration.

*This assumes the amplifier is not broken, or is not being pushed to clipping etc...
If so, then how is it possible that my wife and I hear the same difference in sound when comparing two high-end intergrated amplifiers when using a switch board in a dedicated listening room of our local hifi shop?
 

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Please note, I have no interest in arguing subjectivity versus objectivity. My stance has clearly been made, its even my title on the forum ;). It is rare for either side to budge on this issue, so I just intend to answer non-inflammatory questions.

If so, then how is it possible that my wife and I hear the same difference in sound when comparing two high-end intergrated amplifiers when using a switch board in a dedicated listening room of lour ocal hifi shop?
Amplifiers can be designed to have a specific sound. From adjusting tonality to introducing various distortions etc... There are some esoteric companies that even do this on purpose, actually. In fact, it is one reason many tube amps are so popular.

Additionally, in a sighted, uncontrolled, listening test there are a variety of confounds that would cause non-existent differences to be heard. This is not my personal speculation, but rather, the results of scientific study.
 

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If so, then how is it possible that my wife and I hear the same difference in sound when comparing two high-end intergrated amplifiers when using a switch board in a dedicated listening room of our local hifi shop?
Do you know if they're using any EQ on each unit??? ...How are they set up??? ... That could be the cause :yes:

Maybe they're trying to sell a specific brand and that's why it sounds better (I read that they do it in some stores with the TV's) :yes:
 

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This is an interesting discussion that I've wanted to investigate for a long time. From a science standpoint (including double blind listening test proofs) there is no distinguishable audible difference between amplifiers operating with negligible distortion. This doesn't however, keep me from thinking that some amps do sound differently depending on the speaker they are paired with. This comes from a number of years working with different amplifiers both in home and pro audio in which a difference was noted every time and the opinion was common amongst other people. This is no way qualifies as an objective or scientific test, but is based on experience telling me there may be some (albeit very very little) merit to the thought of amplifier designs sounding different. Some day when the tools and the time permit I would love to conduct some tests.
 

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Discussion Starter #8
So would I!

My reason is that the EP2500 that I use for my subs is rated way better than my main amp (NAD M25), and also very much cheaper. If I could lose my main amp and get a stack of EP2500 my system could be hidden better, be more flexible and alot cheaper. I think I'll do some experiments. Too bad there's no easy way to A/B test two amps on one set of speakers...
 

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I would be very surprised if you noticed any audible difference. However, I cannot tell you how many times I have read from NAD owners the words "that NAD sound"... of course always in a positive manner. I know the NAD T785 worked very well for my Martin Logan's... it was not lacking in power.

Keep us posted on what you do and your findings.
 

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Discussion Starter #10
I know the NAD sounds different from other brands, and probably by design. I know I like the 'NAD' sound, coming from other brands (Denon and Lyngdorf mainly).
I'll try the EP2500 sometime. I have a big system demo for some clients tonight so I won't mess it up today, but I might try it this weekend. Problem is I need to run my system without the subs then, so it'll be very different from what I'm used to. Hm, maybe I could hook the NAD up to the subs just to see what happens. If I don't run it too loud I should get a feeling for what it does...
 

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One thing about the most recent NAD units that I heard rumored is that Audyssey developed a different curve for NAD than they do for other brands. Of course it may be true... just roused my curiosity when I read it. I did not investigate if it was actually true.
 

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Discussion Starter #12
They did. NAD played with the PRO software and developed a new target, and had it implemented in the receiver and processor range. It's plainly called NAD in the target curve selction. It's basically a target with a 'party-hump' in the midbass area and a little more HF rolloff than the regular Audyssey target.

This will not apply in my case though, the M25 is a pure power amp. But the same sound philosophy still apply, I guess.
 

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How about the difference in Carver amps, particularly there older magnetic field amps I owned two of them and they defiantly had a different sound than a more standard capacitor based amp. They sounded brighter and had lots of power right up to there maximum output but look out if you clipped one, they really "snaped"
 

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There can be situations where amplifiers do not sound the same. As I have mentioned previously, amplifiers, just like speaker cable, can be engineered to sound differently. This is not a hard task and is most often found in esoteric brands, but I have also read that some Carver amps equalize the signal as well.

With regard to some speakers sounding differently with some amps: Current requirements are based not only on impedance, but also on phase, both of which are dependant on frequency. So, if a loudspeaker has impedance drops to four ohms at 90 degrees it will present a far harder load than 4 ohms at 45 or 0 degrees (more common). In scenarios such as this an extremely robust amplifier is required to prevent (possibly pleasing) distortion from being introduced. One requirement of the stipulation of amplifiers sounding the same is that they are working within their limits, such a scenario is a perfect example of where an amplifier is not.

If one is interested in properly conducting such a test for valid, generalizable, results. I would be more than willing to discuss proper methodology.
 

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A while back I did a blind listening test with 2 other people comparing a $270 Carvin HD1800 pro amp vs a $1700 PS Audio HCA-2 home stereo amplifier. Our results were that there was no discernable difference. In a later test, we also compared the built in amp section of a Harmon Kardon AVR 635 vs the same PS Audio HCA-2, and again, no discernable difference. And while I'm at it, we also conducted a test at a later date to determine if different DACs resulted in discernable sound quality differences for stereo music playback. We used a "cheap" Pioneer VSX 1014, a "medium" Harmon Kardon AVR 635, and an "expensive" Audio Refinement Pre-2DSP to handle processing with all signals output to a discrete, dedicated amp. Results, yet again, were that there were no discernable differences.

As avaserfi stated, electronics today are to the point where unless someone intenionally creates a design that will alter the sound with a non flat FR or some other "trick", there shouldn't be any discernable sound quality differences. In fact, you should worry a whole of a lot more about the boutique or small "audiophile" companies screwing something up in the design than a big player like Yamaha, Denon, or Pioneer, who have countless engineers, years of research, and big R&D bucks at their disposal.

If you are curious about this topic and are at the point of potentially spending several thousand dollars, I'd highly recommend you do your own well conducted blind listening test. You'll probably find that you can put your money towards other areas which will actually yield a real sound improvement, or at the very least, a much more noticable one.
 

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ya know, i think we should conduct a poll, and see what members think.
 

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Why not just say what you think? Isn't it more interesting to discuss complex matters and get varied reasoning and perspectives than to get poll numbers that allow someone to give an opinion anonomously that may or may not be well informed or thought out?
 

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...idk, to get actual numbers on this as well.

I don't know if I agree with that statement, cuz my KLH receiver and my dads yamaha receiver are roughly the same age in terms of build date, and they have different sound characteristics. Now mine was 189$ his was 500$. It has many similar abilities, but it sounds alot different in terms of playback.
 
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