As an audiophile and an engineer, this is one of the most interesting and useful videos I have watched in a while. Thank you for doing this.

John, please need at least one rant a week from you - ps yours is the calmest and most balanced rant ever

One of my best retail hi-Fi memories is of a time in the early ‘80s when a customer brought his Samsui aircraft carrier-sized super receiver in to audition Polk speakers. It didn’t go up in smoke, but sounded like it wanted to. I substituted the unassuming NAD 3020 and all was well. The look on the customer’s face was priceless.

Soundstage and imaging never gets old for me. Pure magic. Loved music my entire life but never discovered the wonders of music reproduction from a decently setup system until five years ago. I'm 50 now. What a gift. Awesome to hear that an industry veteran like you is still amazed by the listening experience.

My history with music reproduction started when I was 7. Holtz, The Planets, specifically Jupiter. I am now 68. I was never the same person again. I am glad to have known the me that was born that day. Listening to your rant I just can’t believe that we can arrive to the same conclusions. That you and I have the same conceptualización of Science, that we have built the same bridges across different disciplines to land so in focus at the same place. Your contribution is definitely ibroader than building hi-fi speakers. And to top it all you have a kind heart. Very very rare combination of logical mind and pathos. It will be for me a great satisfaction if random and probability -the people who REALLY run our lives - grant me the opportunity to meet you. I use to teach my Communication students in college the 5th book of the Republic by Plato. We do live in a dark cavern and reality is a controlled hallucination. Thanks for your rant. From the heart. 🙏🏻

That was a pleasure. Smiles on my patio with a cigar and cup of coffee. Thanks John

Thank you. Sorry for the delayed response, I just came across your channel. I appreciate your take on audio AND philosophy. Bravo. I particularly enjoyed the comparison about KZfaq playing and what I would call players or working musicians. I could go on and on. Once again, thank you.

My honest respect, John. Very good explanation of your (also my) point of view. Don‘t mind the ignorant guys who aren’t able or willing to understand the limited meaning of measurements. Trust your ears or maybe even more precisely trust your personal perception of music. All the best! 👍🏻🙋‍♂️

I love how the concept of dualism made its way into a hifi rant.

Truly refreshing to hear... I could not stop listening as you seemed to be pulling my exact thoughts out of my head. Bravo, sir!

Very well said and very thought provoking. The questions that always remain for me revolve around how our "being in the world" includes not just perception and utility but also pleasure. Measurements have some use definitely. But I'm also interested in why, at 76 with noticeable top end roll-off in my hearing, I can still tell if a piece is well recorded or well reproduced. Maybe that comes down to how we think we recognize what "well reproduced" means. That simulacrum of reality that our mind and body continuously creates seems to welcome some set of acoustic stimuli more than others.

“If it measures good and sounds bad, it is bad. If it sounds good and measures bad, you’ve measured the wrong thing.” - Daniel von Recklinghausen, audio engineer at EAD and KLH

Dick measuring aside (THD wars, etc.), pursuing measurements is about facilitating greater understanding of what audio parameters subjectively elevate the listening experience to a significant degree, and which parameters diminish the experience. Establishing laudable benchmarks to pursue, and best practices to achieve them. Ultimately build upon that and advance the state of the art. Great rant ... although I've not fully formed my opinion on this, I certainly appreciate your well crafted and thought provoking take.

A good rant is food for the soul, on occasion. 🙂 As a vintage audio collector myself, I can agree with much of your commentary, although, I for one have never taken much notice of measurements as they could not tell me if my ears were going to enjoy it or not. I do pay attention to some needed specs though to match components properly, but there was certainly a degradation of quality after around 1982 from the majority of manufacturers.

Measurements like the ones Amir makes on ASR can let you know how accurately a component can take an input signal and reproduce it. That is what Hi Fidelity is by definition. But it does not mean you will necessarily prefer a more accurate sound. Having objective measurements as a baseline can help you chose which component to purchase and narrow down which to audition.

This is wonderful, perhaps your best video IMO. One way to look at the bigger picture, I think is, “You are not your thoughts” … which expands on ideas of perception and consciousness.

My first system: Pío SX939 receiver, PL51 manual turntable with Shure cartridge and CS99A speakers. I managed stereo stores in the 70’s and worked in consumer electronics 25 years. If I had a nickel for every time I had to explain how specs were ‘fake news’ I’d be a retired gazillonaire.

When I build cables, I never measure them, I build lots of different designs & then trust my ears, different materials measure different, so trusting your ears is the only way to go, great video as usual John👍

Brilliantly all tied together. Well done!

Fascinating ! Reminds me of semiotics in literature. I admire how you can transition so readily from one a simple topic on measurements and their interpretation, to more abstract concepts. The video of the visually impaired music lover was phenomenal. Thanks again.

I agree with everything you said and wish I had known such things before purchasing a Kenwood monster receiver in 1979. It had all of the features one could ever want and had fantastic specs . I later learned that to get such low THD specs some manufacturers used a lot of negative feedback and this can cause time smearing which hides detail. When I got my Carver receiver I heard things that I never knew were on the record or CD , so much so I wanted to listen to my entire collection to hear what I had been missing. I also want to say that I read about 6 studies showing that even though we can not hear above 20KHZ we do somehow perceive it .

Well-played John! Is not a rant but more like a thoughtfully developed epiphany.

One of the brightest moments on this channel ever John. In one word: impressive.

A familiar topic, but one which you were able to elucidate so clearly and with many insights and helpful analogies. Thank you.

Yeah, this is all important to understand. I drew some heavy fire on an audio forum recently trying to explain how designing to pass the FTC power testing regimen and designing an amplifier to physically drive speakers are two completely different things. Most didn’t get it. One guy said the spec sheet included with his receiver "guaranteed" stated performance. I was only in the industry 25 years, what would I know. Nice job.

Thank you for this. I think we will all agree that what we hear is in the real world, it is something real getting to our ears. As a physicist, I know what we hear CAN be measured. The question is what measurements will show good sound, and that we don’t know completely. Jitter is a great example: We used to think bits are bits but then we realized it is not so simple. Thank you.

I love how you talk about this topic. Human has sensory, nerve system, organic tissues, and feelings. And all these connected to minds. Then those all feelings and experiences get to be expressed with our limited words, facial expressions and gestures. Audio hobby starts from that sensation of mixed experiences. Measurements are sampling data, designed with the agenda and based on a theory. So it can only give us certain aspects. Much respect to you, John. I will find my courage to say hello to you if I see you at an audio show next time. I own O/96 and love them so much.

I love your rants and your insights on the hi-fi industry. Keep doing what you do!

John you are such a big influence to me. I hope you get to hear one of my speakers some day. I have spent many hours in front of yours. Loved this video and always learn something!

I wish I could give more than a thumbs up! Marvelous rant!

Gear that measures poorly can sound great, often better. I'm still chasing that sound from the 80s when I plugged my dad's first cd player through one of his old vintage amps with the moody blues on.

actually getting to the later part of this video, there's theory behind why our brain is a predictive machine. It has to do with simplifying to amount of required "processing" and being able to dedicate that processing for other tasks. Namely for the staying alive functions, fight or flight. So predictive processing allows us to only notice anomalies an not have to think as hard to process what's really there.

Not much to say, other than: that was very well received! Enjoyable, even, and it makes total sense. Use measuring for its strengths, understanding the limitation.

What a brilliant video, thank you.

Really enjoyed this, our hearing is an experience in the brain with input from our auditory system modified by our emotional state, previous experience and expectations etc - a very joyful video

Devore speakers seem to not measure well, but people love the sound. Same as Klipsch.

Hey John, love the video, thank you so much for sharing it. While watching I thought several times of one of the best unsung recent poets of New York City, Michael O'Brien. He was a master not just of observation, but of capturing how consciousness works, often in a way that resonates on multiple levels. Here is a short example from his book Sleeping and Waking, the poem "Walking the Dog": "To be men not destroyers." And the Cantos stop./"DESTROYERS" written in wet concrete on 22nd St./as if a vote had been cast. A sign for/"HISTORIES" resolves to "IN STORES."/With each breath of wind more petals sift down. (Highly recommend O'Brien's books.) Your discussion of the participative role of the mind in recreating music (and the particular character and excellence, or lack thereof, of playback gear) is key. Justification by measurement (using a form of evidence that requires no training or imaginative sophistication or listening experience on the part of the listener in forming a judgment--I don't mean that in an elitist way, I mean just being sophisticated enough to have your own taste, to like what YOU like, not just what your favorite reviewer in Stereophile likes) is not just a marketing tool, it is a tool for quantitative (as opposed to qualitative) comparison, and therefore at some level may be folded into status anxiety--specifically in the sense of being a suitable mate/passing along one's genes/making a major production of buying Extra Large condoms (or its equivalent, depending on context, including lording it over other, lesser audiophiles). I recall Art Dudley being pretty scathing about this topic in multiple essays. Not that quantitative measurement isn't valuable in assessing some aspects of quality--John Atkinson has written persuasively on this subject many times--it's just insufficient for discerning whether a new piece of gear is excellent/better than what we already have--at least RE qualities we ourselves have learned to value in playback gear. ("Excellent" in this case meaning it lights up a connecting path or door between the aesthetic world we currently live in, and truer worlds--truer for us, at least.) For me, excellence in hifi gear almost always involves qualities that shift my imaginative and emotional engagement to the music itself, rather than to soundstage depth, leading edges, etc. Though I do think that stuff is cool. I suppose I am looking for a way forward that is also a way back to a time when music was transformative to me on a frequent basis. Thinking now also of your video of listening to Junior Wells' Hoodoo Man Blues on a friend's boom box. Yes! That's it!!! That's the kind of experience I am looking for--but for who I am now, not for who I was then. Thanks again for posting.

John I just recently found your channel and it's amazing how the day and age of the internet can be used to promote more light than dark although it may not be there yet, but finding you and your content that's offered in life experience is like finding a diamond in the rough and a friend I never knew I had somewhere out there. Not this video here alone but basically everything you have pushed out that I've seen so far are the things that I tried to relate with other people in my life which don't really get met with much synergy. Maybe I'll look out and get a neighbor somewhat similar to yourself one day or I'll be that neighbor for someone else one day. Man I really dig your content and please keep it up! I've been in the electrical/instrumentation/automation/communications/radio etc. industry for 23 years and my dream job would be having the ability to be able to afford to start a small premium home audio company building headphone amps maybe to start or like yourself get into the speakers arena. We can only be about 100% sure that we are living this one life and hopefully we can make the best of it because it is a gift regardless how difficult it may be at times. I know gifts don't always come wrapping a bow. Take care brother!

I don't think that measuring things is the problem, as you said you are measuring your speakers yourself, but reducing a complex system down to 3 numbers does not work and that's the point here. It does not even work on subjects that have nothing to do with taste and emotions. If you judge the speed of a car only by acceleration, top speed and breaking distrance, then Max Verstappen wouldn't win a single race. HiFi is a very complex and to a degree even a chaotic system, you can measure almost every detail but you can not really calculate what the sound will be.

Wow, was a real pleasure to listen too, thank you for your observations 🙏🏼

Tom at madisound the guy who designed many crossovers used today once mentioned to me that he was working on 1 that would measure wonderfully on a dynaudio driver set. He would bring out this massive network and let me listen to the results. The better it measured the more lifeless it sounded. I learned much from this.

This video was excellent. Thank you for making this video. I can't tell you how many times what I have heard has been dismissed by measurement cultists, who dismissed what I said outright, simply because it was not experienced in a double-blind study and because my experiences could not be measured. Such a simple thing like hearing a huge difference in my system when changing speaker wire. I inquired why this is, hoping to find a scientific reason behind it. But not only did I not find an answer online, I was met with hatred, anger and disrespect for having the audacity to ask such a thing. They wore their measurement beliefs like a badge of honor, when it was so clearly a badge of utter ignorance. I wasn't guessing about what I'd heard and I was not taken in by snake oil, as they put it. I heard the difference on my own system and someone changed wires when I was out of the room each time and sometimes they didn't change them at all. Yet I guessed right every time. Because I was not guessing. I heard audible differences. My roommate says I have "great ears, and that women are known for having sharp ears." I am a relative newbie compared to him, but the point is that this was not about lusting after gear or being influenced by anyone or any external factors. Someone swapped some wires and I immediately heard and pointed out the differences in the sound. I took notes and it was all done very carefully, considering this was just an at-home experiment in my living room. I thought I'd find tons of information online and I was so excited to learn more about audio, only to be mocked and told that I was a fool. It made no sense. They were so closed off in their beliefs that they would not entertain the idea that I was hearing something that they were not. It doesn't matter that most of them listen on lower end systems and mine is worth around $40k. It doesn't matter that I made sure to use reference records that I know every single note and subtlety of. They simply dismissed my findings. What a disappointment. I was ready for a scientific journey to find out the WHY. And they simply said it didn't happen. They were so ignorant, but actually believed that they knew all. To think that a measuring device could operate like the human ear? Instead of using those devices to get closer to an answer and learn more about what we don't yet know? Anyway, - thank you for articulating these things that I've thought of for so long. I've never seen this problem in the audio world addressed so accurately and clearly. It's a pleasure to listen to. As were your orangutan speakers I had the pleasure of spending a few hours with many years ago. Take care and keep sharing your great stories and knowledge. We need more voices in the audio world. This should be a hobby of endless learning and enjoyment.

The gift of your friend's hearing is called proprioception, I interviewed a friend of mine, a deaf bass player who played in the Puerto Rico Symphony, on a platform soundboard and barefoot. His name is Hector Tirado and he studied with Gary Karr. Thanks for the awesome rant. I like hearing Joscha Bach talk about consciousness, etc. If we live in a simulation, then who gives a shit if I like my Harmonix Tuning record mat!

Couldn't agree more. At the very least, the various measurements proponents need to publish their hypothesis. Without that, 'best measurements = best sound' is an article of faith. I also agree that there is magic and mystery in stereo reproduction of music. Even more, prior to recorded music, humans figured out how to capture sound in a written notation, so that a composition can be reproduced in a different place and time. That I can 'hear' the 14th century because someone wrote down a composition is profound. Writing, too, is an incredible technology.

Finally someone who isn’t an absolute buffoon in the age of forums like ASR talking about the current reality of audio. Great job!

Thank you John, very interesting.

Thank You very much !

You are a pleasure to listen to- very articulate and thought-provoking. Thank you for a great video.

thoughtful reflection

Greatest rant ever🤗🤗🤗 Many thanks for your thoughts about the brain and the controlled hallucination.👍👍

“The beholder’s share”, I’ve thought about that concept, but never heard that term. Thank you. Very interesting discussion from start to finish.

Amen to this, and well said. Gonna have to start trawling e-bay for that shirt, but I doubt anyone would part with one...

Comparing two amplifiers with the same measured results can sound differently, with one sounding better than the other. The reason is that the difference that we hear is based upon the fact that despite the many test parameters conducted, it is a particular measurement that has NOT been done that would explain the difference. I believe that if you can hear a difference, then it can be measured.

I caught this a couple of days ago and very much enjoyed hearing your thought process: a well measured and balanced response to "Measurism". Joking aside, it is reassuring to hear a discussion free of the typical rhetoric attributed to Audiophiles.

Really excellent talk - thank you

Best Video to Date!

As usual, this is one of the most thoughtful videos about the essence of music listening. Thanks for sharing your thoughts John!

I feel this so deeply, science is all about challenging the hypothesis, and exploring the observed phenomenon. Rejecting the observations just because they don’t align with the theoretical model, is downright disturbing.

I really enjoyed listening to this talk! It really resonates with me. Thank you so much! It made me think of this quote: "You are not machines, you are men! You, the people, have the power to make this life free and beautiful, to make this life a wonderful adventure" [Charlie Chaplin in the Great Dictator] 😄

Wonderful dialogue. Thank you for sharing your thoughts. Lots of nuance.

Controlled hallucinations... Very well explained. Not sure if any measurements can really capture the psychoacoustics we experience from listening to music.

Thanks for that John, makes so much sense and well articulated!! 👋👋👋

Just loves these videos!! They just make my day better :D

Fascinating and very understandable explanation of some complicated ideas. Thanks for making this.

Yes, I remember , my phase linear 400 which had great specs got smoked when my friend brought over a old Mac tube amp. A learning moment.😊

Hi John. Recently found your channel and love your content, your passion and insight into your company industry. I repair, refurbish and upgrade speakers, mainly vintage so find your channel great. I'm slowly working through all your videos. Amazing work. Hope to hear some of your speakers one day. Cheers. Matt (UK)

The 22 khz initial response limit was logical. At a good seat in any concert hall (row 10 - 20), you are lucky if you even get 16 khz. FM radio typically had a brick wall filter to kill the stereo pilot tone. Tape heads even at 15IPS limited HF due to the tape head gap. Popular condenser microphones in that era had resonance issues in the 24000 to 30000 hz range (that never were audible due to the head gap!).

Relying solely on measurements is the opiate of the masses 😉

And it’s this open and curious mind on display in this video that enables you to make such wonderful sounding speakers! Some of what you are saying hints at what some of my favorite mindfulness practitioners (Singer, Brach, Tolle) would say when speaking around consciousness and metaphysics. It’s my personal belief that what may sit behind the human brain/mind and can bear witness to the world and our beautiful experiences (like listening to music) is something akin to a soul. When I describe your speakers I say they convey the soul of the music. Okay that’s MY rant. Cheers from Woo Woo California ;)

I remember those days where it was all about the 0.005 THD in the advertising litterature.

Excellent John, more of this please

Thank you In the past I've tried making a similar, yet not so elliquent, argument about cables that, not all things are known. I don't try anymore as life is to short and I'd rather spend my time experiencing. The one thing I don't understand is people wanting that live concert sound in their room. The live experience is great but almost never the sound. Recently I made a list of every concert I can recall going to, about 120 so far. But that list doesn't include street, bar or coffee house shows. I can't recall a single time where "soundstage" was ever involved. This includes unamplified shows a well. There is a small handful that sounded really good. But if i really just want to hear "the music" I'd rather do it at home.

Best hi-fi Rant EVER!!! Thank you

I think of it in art terms. Photo realistic paintings are impressive but lack beauty like a John Singer Sargent or Monet . Instead of using measurements to find a beautiful speaker, they would have to find beautiful sounding speakers and measure them, trying to find common anomalies that they may share. Easier just to listen

Normal people - the audiophile and music communities - have been damaged by measurism. Like all such cancers, pushback occurs years after the crime. Bravo, John.

Subtle harmonic distortion/coloration or frequency shaping can be audibly pleasant but not measure well in a test that penalizes anything but clean, transparent or linear signals. That doesn't mean people like Amir from Audio Science Review are missing the mark. I think it's perfectly valid to prefer the most clean, transparent and neutral system you can get as a foundation. You can always add in some extra mojo to your setup, by having a second set of speakers that are more lively and colorful..or adding some tubes to your chain when you're in the mood-- or even using DSP to add in some spice.. There's also nothing wrong if you prefer to daily drive the magic mojo from the get go. Diff'rent strokes for diff'rent folks.

Thank you John, thought provoking as always.

Well done John. Having someone in the industry step up and point out the obvious, what is measured is only part of a story that we have yet to fully understand and our brains are the best measurement tool, because our brains are the things we want to please, or in the instance of suspending disbelief, fool. That is yet to be measurable.

A short story about Croft integrated amp tested years ago with Stereophile magazine crew (I believe so it was Stereophile). 1st reviewer got it, listened to it and loved it. John Atkinson got it, tested it and measured results were under expectations, actually quite poor one. So JA gave Croft amp to the 2nd reviewer, because he was surprised about the 1st opinion. And the 2nd reviewer loved it too. Even more, the 2nd one was reluctant to give it back to the 1st one :))A friend of my friend has the Croft preamp and amp combo. I hope I will be able to listen to it soon, because it just makes the music so listanable, it is not some "high end" presentation, but something very right is about Croft's simple pre/amp topology, so he said. Good points! I can go along with them. But for me high fidelity is fidelity to natural tone and presentation of instruments, which objectivists - reviewers like Amir and Erin does not consider at all, but also others who does not compare a sound of instruments to a reproduction capacity of speakers or a system, including their rooms, are more or less a great helping advertising tool to manufacturers and are meaningless for me on a journey to a real natural sounding hi-fi system. And most of them do reviews on a safe side - bass, mids, highs, sound stage, imagining, details.... WHAT ABOUT NATURAL SOUND of instruments and voices!?? Anyone could do a small unplugged session in the listening room, maybe twice per year, record it and use this as a reference point and that would be also a kind of "certificate".

Love this. Unfortunately in HiFi most people don't learn this until later that good measurements don't equal good sound. The newcomers to HiFi often chase specs. If you Google " review" one of the first hits is often an ASR forum post "review" with THD and SINAD rankings, usually with Topping and SMSL at the top, very little in the way of listening. I'll hand it to these big Chinese HiFi manufacturers, they knew they could sell a lot of amps with good "specs". The measurements need to evolve. It's obvious that seasoned audiophiles figure out that specs aren't everything when you see that "Late stage" HiFi people invariably have tube amps or tube preamps, which often measure poorly. I left behind my SMSL DS DACs for R-2R DACs that have a more natural timbre to my ears.

Whilst scrolling through my KZfaq inbox, I came upon this video. The title and run time did not enthuse me to watch it. But, for some reason I hit the play button, knowing full well my interest would diminish after a very short period. How wrong was I? An absolutely fascinating and eye opening video! I’ve watched it from start to finish, twice. It has totally rewired my thinking on hifi and everything else our brains interpret via our sensory systems.

The beholders share - in HiFi Love it It lends another creative dimension to HiFi Measure that

interesting, thanks. would like to hear you debate Amir form ASR on this. Perhaps some measurements are valid, others not - it's all down to taste

GM ☕️ Dan D’Augustino said it best . He did an amplifier that ( it wasn’t released) thst measured spectacularly..but sounded like shit ! He always said in the end , specs are for production consistency but to what it sounds like is the final judgement. Music ( at least for this hobby) is a deeply personal thing….get what you like and love the music . Great video 👍👍

Very well said. We listen to speakers, not measurements!

Hi John, congrats to this "rant". So interesting and comforting in a way to hear your thoughts on this very complicated and most likely never-ending story. I bought my first pair of speakers in the early 80s. And, of course, first of all they had to measure well. In those days, according to the "experts", it was all about measurements. By the way, a couple of weeks ago my family and me visited NYC. One day we have been very near to your factory and I asked myself whether to salute you. But it was Labour Day .. Greetings from sunny Spain!!

How can we listen to reviewers over 55 years old with reduced hearing ability ? Go get a hearing test and discover how the midrange hearing had disappeared. Definitely the best investment in HiFi before spending any money … a good hearing aide

Both Measurements and Souns quality are necesary to make an assesment on what ypur going to buy. People that swing only to one side are looking at things with one eye open!!. Not all well measuring equipment sounds good!!. The important of equipment sinnergy and room accommodation comes to prevalance!

🤯🤯🤯🤯🤯 well reasoned, well articulated, well... damn

Their is a King Ding on eBay for 260dollars. One was 400 dollars. That’s some toy eh?

Interesting but not sure completely accurate, John. For example, where did Sony/Philips ever believe humans could hear >20kHz. All that improved were better low-pass filtering. These days, most designers recognize that there is no need for >20kHz material and no need for stuff like "super-tweeters".

The fist thing "science" says about audio is that your observations of sound in uncontrolled setting, with your eyes involved is wrong. That is easily proven and is part and parcel of human perception. So no matter what is wrong with science of measurement, you can be sure that the substitute cannot be the subjective experiences you promote. To wit, who says you made the right decision in having a worse frequency response in your speaker? You are the designer with who knows what hearing ability to determine that. The test would have been a blind, level matched one to determine if that correction was needed or not. You know, when only the sound is heard and evaluated. NOT knowing that one position of crossover switch says this and another says that. Just run that test. It should take just a few minutes. Invite a few audiophiles over, don't tell them what you are doing and run a trial 10 times and see if you get 9 times in favor of your preferred setting. That is how we do audio science. Remember, if your brain can manufacture a band sitting in front of you from two speakers, it is quite capable of fooling you in other ways! As to measurements, we apply science of psychoacoustics to them. Then we can determine audibility. And measurements as far as what I perform at ASR, are a full suite, not one signal as you imply.

Thanks kindly!! Great video !!

Thanks John, Interesting topic.

Attractive 'measurements ' are nice but when the lights go down and the music comes on those things are completely forgotten.

Thank You.

Need more rants! Well done, John. Subscribed. 🙂

Howdy. Yeah. Frequency bandwidth and THD for one sine wave belong to the sixties and seventies. Usually applied for tube amps. It is a good start but yet far away from the listening experience. Next step is to check the rectangle wave response. Are there overshoots and undershoots at the ascents and descents ? Maybe there is residual ringing. If so, it is indicative of long loop neg. feedbacks. I.e. there is time delay in the loop. This does not show in single wave bandwidth measurements, because the sum wave of the sine signal and the phase shifted sine feedback is a sine wave. And further. Check the response of triangle waves. Are the slopes straight lines ? If not there is harmonic distortion. Way easier to see visually than looking at sine waves. Yet still. Check the burst response. Is the amplitude constant during the burst ? If not, it is indicative of that the power supply struggles. There may be compression of the audio. The pumping audio is very annoying to listen to. If these check out the system is ready to for listening evaluation. If not I would not bother if the aim is High End. Regards.

Thank you.

The possible exposure of audiophile equipment measurements as most probable snake oil. Very well done