Working with the human ear: the proper evaluation of audio equipment incl. amplifiers

[HUG-1]

But wouldn't Alan and Hug-1 tell us that volume matching must be science, not art: it cannot be done by ear, or else you're using your ear to test your ear, so it must be done electronically. And when the levels are matched in this way, what were {significant} audible differences are no longer audible.

Bruce

Correct. To quote from this post earlier

3) As there are no standards for the gain (loudness) of amplifiers at the loudspeakers relating to the marking of the volume control knob on the front panel, you cannot be sure how many volts any amp is producing for any volume control position on the front panel. For example, amp A at volume setting 8 produces 18w output; amplifier B produces 41w at volume setting 8 and amp C, which doesn't have a volume control, produces 110w from a fully driven input stage. It is impossible to compare the sound of these without reducing (in this example) amp B to volume setting 3 (to match A's 18w output) and measuring the output of amp C. Who would think to do that?

Can amplifiers be level matched by ear? Absolutely not! That's why this debate will not die. The failure of the ear as a precision instrument is the source of the problem! You can't use your ear to validate your ear!

Either Alan has the weight of one hundred years of acoustic research on his side or he is a liar or mad. Simple as that.

There is not one scrap of evidence in 100 years of acoustic study that the ear can detect and eliminate loudness differences to the necessary precision to allow accurate comparison of randomly selected amplifiers (or CD players or speakers). Can you find contrary evidence in any scientific journals?

[hifi_dave]

Correct. To quote from this post earlier

Either Alan has the weight of one hundred years of acoustic research on his side or he is a liar or mad. Simple as that.

There is not one scrap of evidence in 100 years of acoustic study that the ear can detect and eliminate loudness differences to the necessary precision to allow accurate comparison of randomly selected amplifiers (or CD players or speakers). Can you find contrary evidence in any scientific journals?

I repeat - you are welcome here to make comparisons yourself as I have done countless thosands of times in my chosen career of selling quality Hi-Fi for the past 39 years. I assure you that differences are audible. You might think the differences are small and/or not worth paying for but differences there assuredly are.

[HUG-1]

The deal is already on the table. You come to us with your amps and your CDs. We measure the amps with precision test equipment and set them to exactly the same gain (loudness) within 0.1dB. We will also check the technical specifications including frequency response. Then we connect the A-B instantaneous switchover box. Then you play music and you switch-over 100 times as you wish. The switch-over is operated by a foot switch. Law of average says 50 times you select A and 50 times B as best sound*. If you can do better than that on just 100 switch over (perhaps 60 right guesses) you win yourself a pair of Monitor 40.1s.

If we are wrong about this, the least we can do is put our money where our mouth is and you would have done the whole HUG a great service. Do beware though: in every test like this over the years reported in the hifi press the result is that nobody can hear a difference under these conditions.

Deal?

* Depending upon the amps you may hear a tiny click when they switch or you may not. If you do not hear this click, you will not know that you have switched-over except the switch-box LED confiming relay change-over. No sonic difference upon switching over. But there is a big sonic difference is the levels are not matched exactly.

[EricW]

Law of average says 50 times you select A and 50 times B as best sound*. If you can do better than that on just 100 switch over (perhaps 60 right guesses) you win yourself a pair of Monitor 40.1s.

Ooooh, be careful. I'm no statistician, but I know that even if the results are pure chance, tending to 50/50 over time and given a large enough number, it's entirely possible that within any given sequence there will be less than a perfect 50/50 distribution of results. The larger the number the more likely it is to have an even distribution, but I'd be concerned that 60 out of a 100 may still be within the realm of statistic possibility as an outcome attainable by pure chance alone.

I'd suggest you check with your local mathematician before offering odds.

[A. E.]

...in every test like this over the years reported in the hifi press the result is that nobody can hear a difference under these conditions.

Would you please give the link we can read those previous reports?

{Moderator's comment: they are already here somewhere. Can anyone help please?}

[A.S.]

Would you please give the link we can read those previous reports?...

Sure. This amplifier sonics issue is not new, and that's one reason it's so frustrating because it has burrowed deep under the skin of an entire generation of hi-fi enthusiasts. A good start would be the Moir paper attached. Also, I think it would be worth reading the tribute to the late James Moir and asking oneself if there are contemporary audio designers who are likely to have his breadth of experience not just of hi-fi but of wider engineering.

When we talk of 'blind testing' we mean preventing the listener from actually seeing what he is critiquing: he must judge solely by what his ears tell him and not his eyes. In this regard, the welcoming warm glow of a tube amp versus the antiseptic greyness if a sold state amplifier would obviously bias a listener's observations. Every effort should be taken to judge audio equipment without looking at it: a blindfold is the optimum solution.

However, and there are those who are extremely hostile to the concept of blind testing. For example, here in The Absolute Sound's article The blind (mis)-leading the blind
you will read that when blind tests do not expose fabled differences between equipments, the test itself is dismissed. This is very odd to me. To quote from the above article ...

The latest in this long history is a double-blind test that, the authors conclude, demonstrates that 44.1kHz/16-bit digital audio is indistinguishable from high-resolution digital. Note the word “indistinguishable.” The authors aren’t saying that high-res digital might sound a little different from Red Book CD but is no better. Or that high-res digital is only slightly better and not worth the additional cost. Rather, they reached the rather startling conclusion that CD-quality audio sounds exactly the same as 96kHz/24-bit PCM and DSD, the encoding scheme used in SACD. That is, under double-blind test conditions, 60 expert listeners over 554 trials couldn’t hear any differences between CD, SACD, and 96/24. The study was published in the September, 2007 Journal of the Audio Engineering Society.

The AES is the world's professional audio body. Also:

.... The answer is that blind listening tests fundamentally distort the listening process and are worthless in determining the audibility of a certain phenomenon.

This may be true but it is not valid to dismiss blind listening any more than it is to dismiss clinical trials of drugs which use placebo controls: yes, bias errors can creep in but by and large, a control is an essential tool; and blind listening trials are just another form of control.

I have never met an amplifier designer who has invested the necessary $20 and a few hours to make a relay change-over box. Such a simple device would allow the instantaneous change-over from amplifier A driving the speakers to amplifier B, using a hand held or foot operated switch. I prefer the foot switch because I don't want to hear the click of the switch in my hand. Yet, despite the absence of this most basic equipment, enormously inflated claims about sonic superiority are made about one brand of amplifier over another. The claims simply cannot stand up. First, it's unlikely that amp companies acquire products from their competitors (due to high cost) and secondly, even if they did, without the change-over comparator and careful setting of levels, they have no means of arriving at a valid sonic conclusion. So would any claims about sonic superiority be any more or less valid than those used to sell fancy make-up to middle aged women using pseudo-science? What marketing people call 'puff'.

Incidentally, it occurs to me that maybe you've never been presented with a foot (or hand) switch driving a change-over comparator. So I wonder if you can imaging what you experience when you press the switch and a tiny fraction of a second later (less than a blink of the eye) the speaker is being driven from the other amplifier. I've tried this a few times over the years and I'd like to share my experience with you ....

1. Is there a gap in the music between A and B switch-over? Yes but barely detectable - the room is still singing which masks the gap ...
2. How can I be sure that amplifiers are equally loud? The amp levels are closely matched using instruments before the test starts
3. At the instant of switch over, will I experience a 'night and day' sonic sensation changing from one amp to another? Most probably you will have to look at the LED light on the change-over box to prove to yourself that you have actually switched over to the other amp
4. Are you saying that the switch-over will be sonically seamless? That's been my experience. Some amps produce a tiny audible click at the speaker as the relays change
5. That cannot be true. When I hear these amps at home under normal conditions there is a huge difference in sound: black and white. You are seeing the amps, their levels are not matched and you are not switching over in a blink
6. I don't believe you. That is counter-intuitive to a lifetime of listening to amps. I'm really very sorry to disappoint you but this has been known for over thirty years and occasionally re-evaluated.

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[Takis]

Please, read my post #24

http://www.harbeth.co.uk/usergroup/s...r-©-Alan/page2

Using a single player at a time, levels matched using our ears at first, and then by a test-tone cd and a db meter. All the times, no one could hear a difference, or identify the one amp or the other... NO ONE.

[A.S.]

Just to be clear about this amp comparison subject as I've heard that some other forums seem to have misunderstood our intentions ....

1) We definitely, 100% do believe that people (including me) can, do and will hear differences between amplifiers randomly put in front of us, hooked up, switched on and turned up!

2) We have observed that for psychoacoustic reasons that we do not understand or pretend to understand, when those very same amps are level matched (with test equipment) and then connected to a good quality relay change-over driving one pair of speaker, that when the change-over is operated entirely at random, those big initial differences heard in 1) diminish to little or nothing. So much so that it's actually not possible (in many instances) to hear any discontinuity or change in the music at all, except the minute gap as the relays flick over - perhaps one thousandth of a second. Even that may not be audible. Surprising, yes it is to me as well. This is, I agree, counter-intuitive.

3) We send all those that make amplifiers our good wishes. If the test revealed - and it would be worth a pair of M40.1s - that one amplifier was of such easily demonstrable sonic superiority to all other contenders (I'd buy it immediately) it would truly be a match for our RADIAL cone technology. The entire hi-fi industry would have taken a genuine leap forward and a golden nugget revealed which we'd all do very well to buy. I look forward to that revelation. That designer, that company deserve to be hugely successful.

The way things currently stand, every hifi amplifier designer is claiming that his amp 'sounds the best'. That means that if there really is a golden amplifier amongst the pack, we are missing it due to the marketing clamour surrounding all the other amplifiers. They cannot all 'be the best' can they.

That's our sole point. We wish we understood the human ear better. Exactly why this switch over test 'levels' what are initially significant performance differences is a mystery. Pass this on.

P.S. Link to switch-over box design is here.
P.P.S. As a point of clarification, I never listen to more than a few seconds of music before switching over: listening to an entire track is unthinkable. See the next post ... #44

[A.S.]

Tidying up the server just now, I found a PDF containing a video from a few years ago. I'd forgotten that I made this at the previous listening room and I could film this in much better quality now. Apologies for the picture/sound quality.

The way I work is all about instantaneous change-over. I do not trust my own audio memory. This video shows the foot switch in operation (the actual switch-over box is under the speaker stand). It allows me to compare two speakers instantaneously against each other - an M40 v. an M40.1 - then comparing one with a SHL5, and finally one with the M30. No need to move from the hot spot. No need to listen to the same full track (boring, soporific, teaches you nothing - listening at this time is not for pleasure). Just click-click and change over. You may just about be able to hear the difference in sound picked-up by the camera's inbuilt microphone.

So, when comparing amplifiers you use the switch box in reverse: two stereo amplifiers drive one pair of speakers and can can be switched-over to just as fast as you can hear the speakers change over. Completely foolproof. Totally eliminates memory, and most important, emotion, fatigue and attention drift.

NOTE: I can guarantee that this PDF is fully Adobe compliant (see footnote) and it will open and play the video in the genuine original Adobe Reader X - free here. The clone PDF readers will not play the video content.

>

[123teemu]

The challenge Alan has raised is very interesting indeed. I will follow with great interest. May I suggest this discussion be separated into its own thread?

Also, an alternative switch for the test may be found here: http://www.dodocus.de/highend.htm

Br,
Teme

[Euler]

Ooooh, be careful. I'm no statistician, but I know that even if the results are pure chance, tending to 50/50 over time and given a large enough number, it's entirely possible that within any given sequence there will be less than a perfect 50/50 distribution of results. The larger the number the more likely it is to have an even distribution, but I'd be concerned that 60 out of a 100 may still be within the realm of statistic possibility as an outcome attainable by pure chance alone.

I'd suggest you check with your local mathematician before offering odds.

I'm a mathematician, not a statistician, but I have taught statistics in the dim past. If there's no audible difference between the amps, then each trial is like a coin flip, and with 100 trials the chance of getting outside of 40 to 60 heads, say, is pretty small, about 5.68%. And the chance of getting outside 10 to 90 would be really tiny. Now someone who really could discern a difference between the amps should be expected to be able to pick out the same amp say 90% of the time. If they can do that, Alan and Hug-1 should fork over the 40.1s, since the probability of doing that by pure guessing would be so small.

Bruce

[A.S.]

I'm a mathematician,... If there's no audible difference between the amps, then each trial is like a coin flip...

What I find so inexplicable about the switch over test is this ....

The relay change-over box has an LED which glows when the relays are connecting amp A to the speakers and extinguishes when amp B is connected. In my (limited) experience over the years with this switch-over if it were not for the LED glowing or not (and possibly the smallest of audible clicks) there would be no way of knowing that a switch-over had actually occurred.

Indeed, to be extremely generous to the test subject (and I am under no obligation to do so, but am compelled by fairness) I would allow the tester complete control over when and for how long he wished to switch between A and B. He could switch as many times as he liked. Thousands if he had the enthusiasm. His response, identifying the model 'A' or 'B' would be recorded against the LED on/off status by the adjudicator.

If I was less generous I'd construct the test like this: the LED would be removed from the switch-over box and extended on long wires to be only visible by the adjudicator. The adjudicator would be in command of the foot switch. Without warning and randomly, the adjudicator would operate the relays but would give no clue to the test subject that he had done so. The tester would be instructed that if at any time during the test he heard what he believed was a difference in sound he was to raise his hand. The adjudicator would operate the change-over 100 times and each time look to see if the test subject raised his hand. If at the instant of change-over the tester raised his hand, meaning he had heard a difference in sound attributable to the amplifier switch, that would be recorded as a positive result for him*.

I'm fairly confident that there would be negligible correlation between the actual change-over and the hand raise. In fact, I'd fully expect the hand to be raised and fall when the same amplifier was driving the speakers continuously, triggered solely by some internal process in the human brain.

This is a purely psychoacoustic matter. It is precisely the sort of human observational experiment that reveals just how unreliable our senses are. To deny that, or to fight against it is just silly. We are the product of evolution - this is just the way we are built.

My main thrust is, as I have stated unequivocally: there are far better reasons for choosing one amplifier over another than 'sound quality'. Durability, styling, features to name three.

*I would expect that unless the amplifiers are wildly different in performance (or one exhibits a loud click) he (and that includes me) would achieve 10% success rate identifying the instant of switch-over.

[A.S.]

In 1959, at the dawn of the stereo era, the tube audio amplifier reached a performance plateau. Here is a write-up of the famous Leak amplifier (attached).

Note how the report is entirely objective. I cannot find one word about the 'sound quality' of the amplifier. Clearly the marketing approach of attracting consumers based only on technological arguments was not sustainable. I wonder how this same amplifier would be appraised today - for its sound quality alone?

>

[DSRANCE]

I dunno, you lot getting al hot under the collar about amp-differences.

My belief is that the bulk of any perceived differences in amps is clearly measurable and as much an art on design as designing and "voicing" a loudspeaker. How the power supply sags (or not) under load, how the amp copes with often complex impedance curves, how the amp clips a signal (some ring/almost oscillate, others soft-clip gracefully) and lastly, the damping factor presented to different methods of acoustically loading the bass unit..

Like HiFi Dave, I've recently experienced relatively massive amp differences using new SHL5's - take one of the Sugden "Class A" in comparison with, say, the new little Rega Brio R. The way the music, especially percussion, is portrayed is so different it's almost like changing speakers. On the other hand, Dave has other amps at his disposal that, to all intents and purposes, sound so similar I know I couldn't tell them apart if blindfolded.

I'm certain all the amp-differences I've heard over the years are easily measured - the different generations of Naim amps for example, especially the first transition of the NAP250 from the "bolt-up" era to what's now known as the "CB" era, or the CB era to the current models which sound less harsh and more "cultured" (according to test reports in HFN and HFW, the distortion spectra has broadly changed from excessive odd order harmonics to a more even spread).

Coming back on topic, I doubt I'd be able to "win" a pair of 40.1's because I'd be spending all my time listening to lovely music coming from them as I did recently, via an ancient but still very capable Crown DC300A II of all things ;)

[A.S.]

... Like HiFi Dave, I've recently experienced relatively massive amp differences using new SHL5's...

I reiterate (again) what I keep having to repeat, to quote from post #28 ...

1) We definitely, 100% do believe that people (including me) can, do and will hear differences between amplifiers randomly put in front of us, hooked up, switched on and turned up!

2) We have observed that for psychoacoustic reasons that we do not understand or pretend to understand, when those very same amps are level matched (with test equipment) .... those big initial differences heard in 1) diminish to little or nothing. So much so that it's actually not possible (in many instances) to hear any discontinuity or change in the music at all, except the minute gap as the relays flick over - perhaps one thousandth of a second. Even that may not be audible. Surprising, yes it is to me as well. This is, I agree, counter-intuitive.

I'm wondering where the ambiguity in my statement is. I keep having to repeat 'I expect you to hear a difference between any amps taken off the shelf and randomly hooked up ...' so you are not telling me anything new when you report - understandably - that two amps plonked down in front of you and connected-up sound different. I'm damned sure that they will and do!

It's the tiny mental leap to the next stepping stone that seems to be the problem. The open-minded curiosity that asks whether that sonic difference is still so obvious when the levels are matched. What is the problem with this next step David? Why are we being told - again - by well meaning and intelligent people what we already know to be a truism of random evaluation of audio amplifiers (under non-controlled conditions) that they 'do sound different'? I agree!!!!!

It is a given that under random conditions amplifiers will sound different as I have said so many times. We're trying to eliminate that randomness to see for ourselves if amplifiers still exhibit these notable sonic differences. If the sonic differences are still audible under controlled tests (and they may well be - I am prepared to lose a pair of M40.1s to find out) then you have a proven, simple, cheap (about $20) and effective way to grade the transparency of any and every amplifier you can get your hands on. The winning amp should overnight deservedly become a world-wide runaway success. I only wish I could predict what it would be and invest in the company.

This is entirely about sorting marketing puff from sonic reality.

[Zemlya]

There is not one scrap of evidence in 100 years of acoustic study that the ear can detect and eliminate loudness differences to the necessary precision to allow accurate comparison of randomly selected amplifiers (or CD players or speakers). Can you find contrary evidence in any scientific journals?

To make an analogy, the amplifier is to a speaker what a camera body is to a lens (film photography).

The camera body's main function is to serve as a light tight box. So if one is shooting with the same lens on multiple camera bodies, the resulting image will be unaffected by whatever body is used. So why would one choose a more expensive body if it makes no difference on the resulting image?

Likewise, an amplifier serves as an amplifying device. Nothing less, and nothing more.

With a camera body, ergonomics and reliability are paramount. This is why old Leica M bodies are so highly sought after by contemporary professionals.

This is the approach people should take when deciding on electronics to power their speakers. In many ways the speakers are like the lens (the most important investment, and the one that will make the largest difference). The rest is peripheral.

This acknowledges that people are welcome to purchase whatever amplifier they wish, but this will most likely not result in an (objective) improvement in audio (image) quality.

So choose based on aesthetics, ergonomics, aftercare, brand history, etc.

Nobody is saying that a cheapie $100 Sony receiver is better than a Myryad or Bryston. Because technically they would be wrong. Moreover, when I worked in retail hi-fi, failure rate in the cheaper products was often higher in demo models. However, I don't think I would be able to tell the difference between the Sony and Bryston under controlled listening conditions.

Of course there those people who actually think that camera bodies make a difference <<< CRAZY!!!

[A.S.]

... This is the approach people should take when deciding on electronics to power their speakers. In many ways the speakers are like the lens (the most important investment, and the one that will make the largest difference). The rest is peripheral.

This acknowledges that people are welcome to purchase whatever amplifier they wish, but this will most likely not result in an (objective) improvement in audio (image) quality.

So choose based on aesthetics, ergonomics, aftercare, brand history, etc.

Nobody is saying that a cheapie $100 Sony receiver is better than a ....

Exactly. Having discussed this with our youngest son yesterday, picture, (a marketing graduate, 1st class, Hons.) he recognises and has the appropriate buzz words for how marketers have steered the debate from the real issues (as you state them) towards tertiary and ephemeral 'brand attributes'. He's up on all the latest marketing techniques, and says that this amplifier/camera body issue is now the conventional way of marketing goods in saturated markets. Even bread is not marketed for nutritional value (surely its core function) but for some lifestyle related factors.

He also added that the advent of 'digital media' (like this forum and Facebook etc.) had encouraged consumers to develop and reveal a 'virtual personality' - products which they in their virtual world would own if they could. It's unlikely that the durability of an amplifier would be a marketable attribute, but excite the virtual (or actual) consumer with the fantastic and unsubstantiated notion of 'enhanced musicality' and they see and want and aspire to that benefit. Durability inspires no-one other than military hardware users.

He chuckles at the slide from pure objectivity (the Leak report from 1959) to pure subjectivism because that has led the consumer right into the eager hands of the marketing boys from which there is no escape. It's really depressing.

>

P.S. Be in no doubt about the vital importance of marketing in our modern, post-industrial world. A 25 year old UK marketing graduate working for a small-medium sized UK advertising agency (David work in the IT industry) can expect a salary of around US $50,000 pa, perhaps twice that of an engineer. Marketing is really important to sustain consumption, and all our life styles.

[muypogi]

To make an analogy, the amplifier is to a speaker what a camera body is to a lens (film photography).

The camera body's main function is to serve as a light tight box. So if one is shooting with the same lens on multiple camera bodies, the resulting image will be unaffected by whatever body is used. So why would one choose a more expensive body if it makes no difference on the resulting image?

Likewise, an amplifier serves as an amplifying device. Nothing less, and nothing more.

With a camera body, ergonomics and reliability are paramount. This is why old Leica M bodies are so highly sought after by contemporary professionals.

This is the approach people should take when deciding on electronics to power their speakers. In many ways the speakers are like the lens (the most important investment, and the one that will make the largest difference). The rest is peripheral.

This acknowledges that people are welcome to purchase whatever amplifier they wish, but this will most likely not result in an (objective) improvement in audio (image) quality.

So choose based on aesthetics, ergonomics, aftercare, brand history, etc.

Nobody is saying that a cheapie $100 Sony receiver is better than a Myryad or Bryston. Because technically they would be wrong. Moreover, when I worked in retail hi-fi, failure rate in the cheaper products was often higher in demo models. However, I don't think I would be able to tell the difference between the Sony and Bryston under controlled listening conditions.

Of course there those people who actually think that camera bodies make a difference <<< CRAZY!!!

On the camera analogy, in the days of pure analog cameras, that may be true, but with today's digital bodies, digital processing engines, in-body image stabilization, the camera body matters quite a bit. Of course, at a certain skill level and usage parameters, one can rightly assume that you can stop at a certain camera body level and spend the rest on lenses.

Put it another way, my current micro-four thirds Lumix GF-1 is leagues ahead of my first generation Canon D30 digital camera, not to mention my Canon G1 first gen point and shoot . . . today's digital bodies take care of noise, image processing, level of detail. Lenses just make sure that the camera is able to capture what is available in the first place.

Kinda like speakers, but in reverse . . . you can't expect your million pound hyper expensive components to sound good using Sony boombox speaker specials . . .

[A.S.]

You will have read earlier about my (perhaps misplaced? - we'll see) opinion that under controlled conditions, amplifier that exhibit a marked personality under random conditions, seem to lose their personality.

It occurs to me that we need not just rely on one pair of ears (the 'participant') to hear the difference on switch-over from A to B. Should we trust just one participant? Shouldn't we all share in the experience as if we were present at the experiment? Shouldn't we record experiment for subsequent analysis and interpretation?

So here is my suggestion: we record the audio signal that is being fed to the one pair of speakers on the outgoing side of the amplifier A-B comparator directly to a high quality 96k sound card and hence to a PC unconnected in any way with the tests as a wav file into, say, Adobe Audition. We could even record from a microphone onto an entirely unconnected track, or perhaps even simpler, to an MP3 recorder, the chit chat that accompanies the switch-overs, then 'merge' the stereo music and the commentary as a three-track session. In addition, as the Harbeth R&D facility has 720p High-res multi-camera recording facilities built-in (to record product development and evaluation), a video could be recorded (onto yet another unconnected PC) of the entire set-up, listening and discussion session. This would provide, for subsequent forensic analysis the entire process including me, the participant, the adjudicator and any others. There would be nowhere to hide (except perhaps the toilet, where the acoustics are, well, not ideal).

I suspect that there will be a small click when the relays disconnect from A and change over to B, and this small click (and the accompanying blink-of-an-eye gap in the music due to the relay contacts in flight) will provide clear evidence on the recording software's waveform that a change over has really taken place. It would be a simple matter to save that resulting .wav file and post it here for the wider readership to decide for themselves if they can hear a sonic difference in the music before or after the change-over.

I'm wondering what objections will be raised to this? 'All rigged as a publicity stunt' perhaps?

[Macjager]

While I would love to see and hear this comparison, especially if you could get some really fancy-schmancy hi-end unit(s) to test. I suspect that you would probably have to get some independent audio engineering firm (or Almighty God himself) to confirm that you are not "rigging" the test in flavour of your position..though who knows why this would be as you are testing amplifier beliefs and not comparing speakers...

I imagine as well, that no matter what the outcome is, you will have naysayers flapping their gums in opposition, quoting such arguments that scientific tests do not reveal the mysteries that only an audiophile can hear...whatever the heck that is... But, I still think it would be great to set up the experiment to test your theory.

Cheers

George