Is there a point of diminished returns with amps and Harbeth 30.1s?

I would see if the Cable Company has any more Audience AU24 show demos at 1/2 price. Excellent sound and very easy to work with.

FWIW I have used AU24E with my 30.1 all along, and have been quite happy.

Alan Shaw has long welcomed any debate on his opinions regarding cables and amps.

This is nonsense. He largely discourages such debate, and considers his views to be facts, not opinions. And the condescension towards those who think otherwise is often palpable.

In fact he once even offered a pair of his top of the range M40s to anyone that would be willing to undergo an unsighted amplifier comparison test. 

Level matched of course.

Unsurprisingly, despite the endless online amplifier hullabaloo / advertising / promotions etc there were no takers.

I'd need to see the actual challenge, but the way that you present it is likely to be disingenuous at best. Shaw, and those who share his views, have been forced to admit that amplifiers can indeed sound different, but argue that it would only be true of those which produced a certain (unspecified) amount of distortion.

They scoff at the likes of Nelson Pass, who is fully transparent about his choice to "voice" at least some of his amps with a certain amount of Second order harmonics, because they are not as neutral as possible. 

Anyone who claims that all amplifiers sound the same is, to put it kindly, on very shaky ground.

One final point: level-matched AB-X testing is undoubtedly a very valuable tool, but in practical terms, very difficult to achieve. Two (or more) amps, using exactly the same speakers, interconnects, etc.?

Good luck with that.

I’ve never really understand the usefulness of blind tests. Do people actually know what they prefer in a short listening A-B session? 

I agree that this is potentially problematic, but to be fair, such tests are not about preferences, but differences. In other words, can the listener simply and consistently distinguish between components, irrespective of which they may prefer.

But while the science suggests that humans have very short auditory memory, I'm with you on the value of listening to longer stretches of music in order to make confident judgments about differences in components.

@cd318

This seems to be the main problem the anti blind listening test brigade have.

Whoa there, big fella. You were well off-base in your original post re: the Harbeth User Group, as I noted above, and now you're sounding even more like you have been sipping the HUG Kool-Aid.

The suggestion that those who believe that there are audible differences between amps, and/or cables, etc., are necessarily against blind testing is ludicrous.

As I mentioned in a previous post, this is not something that is easy to set up, at least properly. So, there is a rather meaningful difference between being "anti blind test" and being unable to easily set up, or take part in them.

Here is an interesting thread featuring a highly regarded member of the Audio Science Review forum. Note both how complex it can be to set up, and record all of the relevant measurements, and that he did hear a difference between the two amps.

https://www.audiosciencereview.com/forum/index.php?threads/ab-x-testing-of-power-amplifiers.20464/

@cd318

The problem with your perspective on this issue, one that, in my view, is shared by a good percentage of the HUG members, is that it is too rigid.

Few would argue that anecdotal experiences are as broadly compelling as carefully executed, published studies, but to essentially lump them all together, and so easily dismiss them, reflects a rather closed mind.

To use just one of many examples of why I believe that to be the case, consider a poster on the Audio Science Review known as "DonH56". He is described as a "Major Contributor" and "Technical Expert", and his background, as displayed on his profile, is:

Design and now validation electrical engineer, focused on high-speed (GHz+) analog and mixed-signal circuits. Did a fair amount of audio design in my youth, including tube and SS preamps and power amps, and a servo-controlled subwoofer back when they were new and few.

I was principal trumpet of the Pikes Peak Philharmonic orchestra, have played in a few jazz and big bands around the area, led the trumpets for the Tri-Lakes Music Association for many years, done a few "pro" gigs, and sometimes play at church.

So, given that the ASR is likely the most broadly skeptical, and science/test-based audio forum in the world, it is safe to say that this member is, to put it mildly, no fool.

I noticed one of his posts on a thread related to the very topic that we are discussing, and have excerpted some bits, and linked to it below.

My assertion is usually weasel-worded as "most SS amps operated within their linear region driving most typical speakers will sound the same". Lots of ambiguity because I have not listened to, let alone measured, a large sample of amps connected to a similarly large sample of speakers any time recently. Treat all that follows as opinion.

***

I suspect few of us would have a problem distinguishing a SS amp from a tube amp. The differences, measured and heard, are large enough to be clearly audible on most speakers.

***

The gain structure and noise floor of the amp is in play as well; one of things I (many people) found years ago was, in blind testing, an amp with a higher noise floor was readily distinguished from another amp. We did a test with two tape (yes, 1/2" tape at that time) loops playing the same music selections using a couple of big SS amps (have forgotten which, Krell, Threshold, and Levinson were in the store at that time, among others). The speakers I’ve forgotten but I think were either Magnepan MG-20’s or B&W 801’s ca. 1982’ish. We might have run with both speakers, too long for me to recall. We inserted a 2 s silence between the selections on one tape, and went straight from one selection to another on the other. The selections were a mix of music but did not have very quiet (silent) passages. Gain matched the channels, natch. With the 2 s gaps, people easily picked out the "noisier" amp, and commented how it "filled in" gaps between piano notes, drum strikes, and such. Without the gaps, nobody was able to tell the two amps apart. IIRC the noisier one was class A but had fairly low SNR, like 80 - 90 dB unweighted, whilst the other amp was something like 100+ dB.

https://www.audiosciencereview.com/forum/index.php?threads/double-blind-tests-did-show-amplifiers-to...

Note how he reports that the difference between how subjects were able to distinguish between the two amps with two seconds of silence between the selections, but not without. That alone provides a potentially important insight into why the results of "classic" blind-tests may not necessarily tell the whole story.

This person is an electrical engineer who has designed and built amplifiers, and a professional musician to top it off. Yet while he is broadly in agreement with those who claim that amps sound the same, his experiences have led him to the conclusion that it is not always the case.

Not so easily dismissed, in my view, and there are many other, similar examples of compelling anecdotes to be found.

@jjss49 

I agree. 

 A straight wire with gain as Quad's Peter Walker once said. Didn't he also claim that he didn't need to listen to his amps? The measurements alone told him everything he needed to know.

This is a view that most amplifier designers disagree with, not to mention the vast majority of audiophiles. 

Measurements do not tell the whole story.