Cambridge Audio CXA81 S2 vs Rotel RB 1552 Mkii

[voodooless]

Somewhat of a contradiction. People claim nobody can hear the difference in amps, but then refer to "inaudible" test differences in making their own amp selection.

If you can't hear a differences....let me select your amp. See how you like that.

Audibility isn't really a selection criterion. It's as simple as that.

 

[Count Dacula]

"Simple"? Your unstated criteria for an audio amplifier isn't actually audio? I could make a list of criteria, but I think we are stuck on inaudible measurements as a possible key.

I get that, but I think the issue right now is agreeing that different amps have a distinctly different sound. Do they not?

ABX? I get to pick out the two amps, right?

 

[Count Dacula]

AI Overview


Yes, audio amplifiers can sound different, but whether you will hear a difference depends heavily on the specific equipment, how hard the amplifier is working, and how it interacts with your speakers. [1, 2, 3]The audio community is split into two main schools of thought regarding this topic: [1, 2]Why Amplifiers Can Sound DifferentSpeaker Interaction and Output Impedance: An amplifier's output impedance (resistance at the output) combines with your speaker's changing electrical resistance. High output impedance can alter the frequency response, causing audible shifts like softer bass or a roll-off in high frequencies. Tube amplifiers often have higher output impedance and tend to color the sound more than solid-state options. [1, 2, 3]Power Limits and Clipping: If an amplifier runs out of power during loud musical peaks (transients), it clips or distorts, which sounds harsh or compressed. An amplifier with more headroom or power reserves handles demanding dynamics cleaner than an underpowered one. [1, 2, 3]Design and Distortion Profiles: Different classes of amplifiers (such as Class A, Class AB, Class D, or tube designs) distribute distortion harmonics differently. While these numbers might measure very low on a bench, the specific harmonic profile can sometimes create a subtle "warmth" or "brightness". [1, 2, 3]Why Many Amplifiers Sound IdenticalTransparent Performance: Well-designed, modern solid-state amplifiers operating well within their power limits generally measure flat across the human hearing spectrum (20 Hz to 20 kHz) with negligible distortion and noise. [1]Controlled Testing: In double-blind ABX tests (where the listener does not know which amplifier is playing and volume levels are precisely matched), many audiophiles and engineers cannot reliably tell the difference between two clean, competent amplifiers. [1]Perceived Bias: Sighted listening—where you can see the gear—often introduces psychological bias. Knowing an amplifier is expensive, heavy, or branded differently can trick your brain into perceiving better sound quality or wider soundstages. [1]

 

[VintageFlanker]

Cambridge Audio CXA81 S2, Wiim streamer Pro Plus (as transport)

There's precisely no point for the WiiM Pro Plus as a transport. The purpose of the Pro Plus being to have a very accomplished DAC (BTW better than the Cambridge's one), stock.

 

[voodooless]

Oh dear.. classical AI slop that you get when you put zero gardrails in your promos.

My AI response:

Yep. That is almost a textbook example of what happens when someone asks an LLM for an authoritative answer and doesn’t constrain it to actual evidence.


The amusing bit is that the first two mechanisms it gives are perfectly legitimate: output impedance interacting with speaker impedance, and clipping/power limitations. Those absolutely can make amplifiers behave differently.


Cambridge Audio CXA81 S2 vs Rotel RB 1552 Mkii | Page 2 | Audio Science Review (ASR) Forum.pdf


Then it wanders into:


“Different classes of amplifiers … distribute distortion harmonics differently. While these numbers might measure very low on a bench, the specific harmonic profile can sometimes create a subtle ‘warmth’ or ‘brightness’.”


That’s classic mush. Yes, distortion spectra differ. But “therefore subtle warmth/brightness” is precisely the audibility claim that needs quantitative support. If the distortion products are below audibility, their profile doesn’t magically become audible because one happens to be second harmonic.

Then:

“many audiophiles and engineers cannot reliably tell the difference…”

That wording is another giveaway. It subtly turns the actual question—whether people can discriminate particular amplifiers under controlled conditions—into some people fail to discriminate them. Those aren’t equivalent propositions.


And finally:

“Knowing an amplifier is expensive, heavy, or branded differently can trick your brain into perceiving better sound quality…”

Expectation bias is real, but this is pop-science phrasing presented as though price/weight specifically have been demonstrated to “trick” this listener in this comparison.

So your response —


“classical AI slop that you get when you put zero guardrails in your prompts”


—is rather apt.

The funniest part is Count Dacula presenting an “AI Overview” as evidence in an argument about objective evidence. The model has basically generated a plausible-sounding synthesis of audiophile talking points, complete with [1,2,3], without us even being shown what [1,2,3] are. That’s not evidence; that’s asking a stochastic parrot to referee the argument.

As to your examples: nobody ever said that all amps sound the same! But properly designed amps that work within their operating limits will sound the same. That is an important difference and is also where the measurements come in.

Your first amp is clearly broken, it will probably be audible. The Carver is a poor amp as wel. It does not even have a linear response and it’s output impedance is too high. This might also make it audible. These are just (very) poor amps. They are bad at what they are supposed to do: simulate a wire with gain. It’s like comparing wine to grape juice.. you and your AI pal just built a giant straw man!

 

[RandomEar]

Somewhat of a contradiction. People claim nobody can hear the difference in amps,

"People" don't claim this in the form you suggest. The common theme around ASR is that properly designed amps which measure good enough and don't clip in the envisioned test scenario cannot be told apart in a blind and level-matched test. So it's not "nobody" and it's not "all amps". There are obvious exceptions like tube amps with high output impedance and less obvious ones where the manufacturer simply decided to color the sound to an audible degree (instead of creating an actual HiFi device).

but then refer to "inaudible" test differences in making their own amp selection.

If you can't hear a differences....let me select your amp. See how you like that.

Not everything is about audibility. There's many, many other aspects like power, available inputs, price or the color and size of the case. So no, it's not a good idea to let other people roll the dice on which amp you will get.

 

[MaxwellsEq]

Somewhat of a contradiction. People claim nobody can hear the difference in amps, but then refer to "inaudible" test differences in making their own amp selection.

If you can't hear a differences....let me select your amp. See how you like that.

Quite a lot of poor logic in your post. Or perhaps you are not paying enough attention.

Your statement: "People [who are these people?] claim [who is making a claim and about what] nobody [who do you include in this group 'nobody'] can hear the difference on amps" is clearly a strawman.

Of course amplifiers can sound different. A broken amplifier often sounds different. A noisy amplifier buzzes, hums or hisses. An amplifier with an output transformer can have a character defined by the transformer's linearity, hysteresis and low frequency handling. A high output impedance affects how an amplifier interacts with speakers. Insufficient power, voltage or current drive can affect the sound of an amplifier when driving difficult loads or when playing loud. Incorrect gain-staging can affect how people experience an amplifier.

I've not seen anyone on ASR trying to defend a blanket statement about amplifiers sounding identical. Read more of people actually say before coming up with a weak strawman like this.

 

[Count Dacula]

So then, where is the limit of audibility, since now we agree these speakers can sound different on different amps, whew. Where is the line then, does an amp need to be "broken" to have a sound signature?

Instead of relying on dubious 40 year old "tests", how about the immediate task of explaining why my similar bunch of amps actually sound way different (to me ). It's easy to claim that people (like me ) are dead wrong about SQ, then go hide behind this study that nobody actually read nor understands. This and the Richard Clark amplifier challenge are classic1970's print-pump-rag hokum disguised as "science", just like Biigfoot or the Loch Ness Monster

 

[Svend P]

how about the immediate task of explaining why my similar bunch of amps actually sound different (to me

That one is easy: because you listen with your eyes. You have to test blind and level matched

Audio Blind Testing - You Are Doing It Wrong! (Video)

Just uploaded a video on the basics of performing controlled tests in audio. It was motivated by saving myself text in having to write all of this down when telling someone who to do these tests right. And as a counter to a few online personalities to keep saying they do "blind" tests yet when...

www.audiosciencereview.com

 

[Count Dacula]

Oh dear.. classical AI slop that you get when you put zero gardrails in your promos.

My AI response:


As to your examples: nobody ever said that all amps sound the same! But properly designed amps that work within their operating limits will sound the same. That is an important difference and is also where the measurements come in.

Your first amp is clearly broken, it will probably be audible. The Carver is a poor amp as wel. It does not even have a linear response and it’s output impedance is too high. This might also make it audible. These are just (very) poor amps. They are bad at what they are supposed to do: simulate a wire with gain. It’s like comparing wine to grape juice.. you and your AI pal just built a giant straw man!

Stay triggered.

The Sound of Audio Amplifiers: Can you hear a difference between Amps?

This article explores the technical reasons why audio amplifiers can sound different. Audio measurements can help explain why things look different but audibility isn't always so cut and dry.

www.audioholics.com

 

[Beave]

 

[voodooless]

Except that assumes I actually have a bias to project onto the equipment. Thanks for assuming that I lack objectivity

You are human (as far as we know). Therefore you are biased and lack objectivity. You cannot control this. It’s just how we operate as a species. You are not special in this.

Stay triggered.

The Sound of Audio Amplifiers: Can you hear a difference between Amps?

This article explores the technical reasons why audio amplifiers can sound different. Audio measurements can help explain why things look different but audibility isn't always so cut and dry.

www.audioholics.com

The reasoning in that article is hilarious:

Hirsch suffered from no such ego-based limitations, and therefore his findings were more defensible from a strictly scientific standpoint

The article is full of this kind of logic tomfoolery.

 

[MaxwellsEq]

how about the immediate task of explaining why my similar bunch of amps actually sound way different (to me ).

They sound different to you because you are a flawed human being along with the other 8.3 billion human beings, including me.

Compared to a microphone and top-flight ADC, your ears+brain are genuinely terrible at reliably capturing audio events. But because of psychological bias you are simply unable to detect your brain fooling you.

Everybody on ASR has "heard differences" which simply turn out to be caused by psychological bias, or by insufficient precision in settings exact same levels, or a general insufficient grasp of how proper experimentation and analysis is done.

 

[Count Dacula]

You are human (as far as we know). Therefore you are biased and lack objectivity. You cannot control this. It’s just how we operate as a species. You are not special in this.


The reasoning in that article is hilarious:

The article is full of this kind of logic tomfoolery.

Hard to take you seriously, since you couldn't even find this link when AI provided it. Also I see you struggled with the material.... biased before erven reading it, another great ASR result

 

[Svend P]

Hard to take you seriously, since you couldn't even find this link when AI provided it. Also I see you struggled with the material.... biased before erven reading it, another great ASR result

If your DUT doesn't affect the frequency response, the odds are it will not affect the sound. And amplifiers in general do all have a flat frequency response.

 

[voodooless]

Hard to take you seriously, since you couldn't even find this link when AI provided it. Also I see you struggled with the material.... biased before erven reading it, another great ASR result

Ah yes, nothing more to defend, so let’s attack the people. Great reasoning!

 

[Purité Audio]

Where did I leave that stake and mallet.
Keith

 

[voodooless]

Where did I leave that stake and mallet.
Keith

Don’t forget the garlic

 

[Count Dacula]

Why not go point-for-point with the "hilarious" article? Because you can't.

On the scope, we could clearly see that the Marantz produced large amounts of 4th-, 5th- and 6th-order harmonics when it was pushed into clipping. A Pioneer receiver there for comparison was better behaved and its distortion was composed mostly of 4th-order and lower components. An AR receiver showed by far the best distortion behavior, with most of its harmonics being very benign-sounding 2nd- and 3rd-order products. Now, finally, there was a concrete, repeatable, tangible explanation for why some amplifiers sounded better than others when pushed into clipping.

All from people with more faith in test equipment than the human spirit. Jesus himself could make a special appearance to share his experience, and you (people) would badger him and gatekeep him to the next town, or site. All the while quoting failed science which you dont quite understand how it's no better than any other opiniun, except it needed a rigged scheme to support it.

I would have tend to have agreed with the majority here, but experience has shown me otherwise. You call that a fault, but the fault lies in the idea that all amps, mics, speakers, instruments, sound "the same" with vague caeats about operating within design parameters. Well, don't they all operate that way? I appreciate how little support you (people) would get in the real world, or even inside your own industry for these ideas. Designers, DIYs and Creatives would be fully opposed, do you understand why? Nelson Pass is still over there giving tips on modding his Adcoms, dont' you get it? That's right, you never designed an amp, wrote a song nor learned an instrument, but you're an expert on....counting inputs!

No, I don't mean the snake oil verses Benchmark test, I mean, LIKE FOR LIKE amps, such as these Q350s are intended for. I have more than a few. See how it doesnt' matter how long I've had mine, how many different amps and associated KEF products I've compared, nfw. I MUST be wrong in order for you to be right. That's the world you're living in. Not one where you've owned your Q350s twice as long, or tried them with twice as many amps or owned twice as many KEFs side by side (I think I have 11 pairs) or how many 1000s of hours I've logged in major recording studios. NO, because if you had all that RW experience, you won't need to rely on 40 year old junk science to form an opinion that you're so very sure of. So your lack of experience forces you to take a position that is really irrelevant.

Enjoy your super-smooth 300w x2 into 4 ohm sound.

 

[Purité Audio]

"It's easier to fool people than to convince them that they have been fooled"
Keith