[KeithEmo]

I already have my answers....

You used a single pair of headphones and a single amplifier.
But what if the differences are there - but aren't audible on that particular, and very narrow, sample of test gear?
(You might try the same comparison using a pair of Stax or even Koss electrostatic headphones... which are both known for extremely accurate transient response.)
(I'll have to admit that I'm also somewhat dubious that the output of an iPod can drive a pair of headphones well enough to not obscure something...)

I use my last Mac Classic iPod as my control source. I compare everything to it, and if they sound the same as it, they sound the same as each other. I already answered the questions about the headphones I use. No need for an intermediate amp for iPod or HA-1. Just a headphone splitter.

Are you really interested? Because I've already answered these questions for you. Set aside your bias and ego and just try to figure it out logically.

 

[Davesrose]

Have you ever seen how an iPhone measures? Would you like to? You can compare it to your system.

You already linked a link once: it's frequency range doesn't compare to the Benchmark...sorry.

 

[bigshot]

When I say "for purposes of listening to music in the home" I mean that I compare using a music file at normal listening levels. I do level matching and direct A/B switching.

I'll read more of your post later. I'd appreciate it if you would stick to the point, which is a DAC that clearly sounds different where it's possible and practical to set up a test to confirm your test.

But what if the differences are there - but aren't audible on that particular, and very narrow, sample of test gear?

Then I would say that it's either not "clearly audible" and wouldn't qualify as "not a subtle difference at all", or I would say that there might be something wrong with the test where the difference was detected.

If well reviewed $1200 planar magnetic headphones aren't good enough to detect the difference, is it really a clearly audible difference? How could Stax be THAT much different than PM-1s? And if it sounds the same on every set of headphones BUT the Stax, does it really matter to anyone but Stax owners?

You're just going back to creating impossible possibilities again. Goal post shifting. Show me a DAC with a difference I can verify. I'm not looking for excused to invalidate your test. I'm looking for a way to validate it. You are the one that is making that difficult. That makes me wonder if you are really sure of what you say yourself. Wouldn't you be confident that a difference should be clearly audible on other good systems if it was on yours? I'm confident enough to invite you to compare any of the units I've compared to make sure they sound the same.

 

[bfreedma]

You already linked a link once: it's frequency range doesn't compare to the Benchmark...sorry.

Are the FR differences within the range audible to humans?

 

[Davesrose]

Are the FR differences within the range audible to humans?

Yes, down below 20hz and well beyond 20khz (iPhone starts rolling off after 20HZ and then around 16khz). I'm 40, but I've tested my hearing and I still hear 17khz...there's also arguments about harmonics and realistic sampling of sound for going above 20khz.

 

[KeithEmo]

That might be interesting....

I tried looking up the specs on the iPod Classic....
But here's all I could find: https://support.apple.com/kb/SP572?locale=en_GB
The headphone output is specified as: "20 Hz to 20 kHz" with "32 Ohm earphones".

And, when I looked at the latest iPhone, I couldn't find any audio specs at all (although I assume SOMEONE has them).
Here's Apple's page on the subject:
https://www.apple.com/iphone-xs/spe...id_294525206764&cid=wwa-us-kwgo-iphone-slid--

Here are some actual measurements Ken Rockwell did on an older model:
https://kenrockwell.com/apple/iphone-6s-plus-audio-quality.htm

It's actually quite good, although he noted an output impedance of about 6 Ohms...
And a resulting frequency response variance of +/- 0.2 dB with a "typical pair of 32 Ohm headphones"...
All of which are "OK but not great"...

I guess we should assume that the new models are better...

Have you ever seen how an iPhone measures? Would you like to? You can compare it to your system.

 

[bfreedma]

Yes, down below 20hz and well beyond 20khz (iPhone starts rolling off after 20HZ and then around 16khz). I'm 40, but I've tested my hearing and I still hear 17khz...there's also arguments about harmonics and realistic sampling of sound for going above 20khz.

Can you provide a reference for that? I’m not able to find any FR measurements of recent iPhones that show roll off under 20hz or around 16khz.

 

[bigshot]

Can you provide a reference for that?

So we can be specific, I have a 6s plus. Here are measurements. https://kenrockwell.com/apple/iphone-6-plus.htm#meas

It makes absolutely no sense that my iPhone might have a response imbalance that precisely matches an imbalance in over a dozen other components by different manufacturers. It's more likely that all of them are audibly transparent.

Keith, look up the impedance specs and sensitivity for the Oppo PM-1s. They work fine with the headphone out of the iPod and iPhone. If headphones require different impedance specs, you just do line out to a headphone amp and VOUALA! you have audible transparency. Impedance mismatches are the fault of the headphones, not the DAP. The DAP works fine with the headphones designed to work with it.

 

[bfreedma]

So we can be specific, I have a 6s plus. Here are measurements. https://kenrockwell.com/apple/iphone-6-plus.htm#meas

That’s why I’m asking for a reference supporting the previously made claim that the iPhone doesn’t have a flat FR. All of the response charts I’ve seen including Ken Rockwell’s show a flat FR well beyond human audibility.

 

[bigshot]

Yes, down below 20hz and well beyond 20khz (iPhone starts rolling off after 20HZ and then around 16khz)

You're mistaking the iPhone for the AAC codec. AAC 192 and below does exactly what you say. That's why I use AAC 256 VBR that extends beyond the limits of human hearing.

The difference between 16kHz and 17kHz is extremely small- not even a single note on a piano. But it doesn't matter because there isn't much up there in recorded music anyway. All that stuff about harmonics is hooey, because those frequencies get masked and disappear completely into the room if the recording isn't really close miked. That stuff is audiophool meat and potatoes. The frequencies that matter are the ones in the middle, particularly the upper mids/low treble. The least important frequencies are the ones in the top half octave of human hearing (15kHz to.20kHz)

 

[Davesrose]

Can you provide a reference for that? I’m not able to find any FR measurements of recent iPhones that show roll off under 20hz or around 16khz.

Well it was from memory from bigshot's rhetoric that's now been linked above of the 6S (and with more loads, Ken says it's good with the slight roll off being good and could sound warm). So another argument about headphone stage instead of DAC. I'm also into photography and I know that Ken Rockwell is not much of a source for accurate information (I once actually informed him about why extended ISO doesn't have better DR).

 

[bigshot]

Rockwell's facts are impeccable. He just has unpopular opinions. I understand that myself completely. Some folks just don't want to be reminded of the facts if they don't match their personal opinions.

 

[Jaywalk3r]

I'm just curious....
You said "Every one of them sounded the same for the purposes of listening to music in the home"....

Does this mean that you actually did in fact conduct a bunch of proper, level matched, double blind tests between a bunch of them....

That standard is only required when one is trying to justify rejecting the null hypothesis. The null hypothesis is, by default, not rejected. It is rejected only in the event that the actual observed data is very unlikely to be observed if the null hypothesis is, in fact, true.

 

[bfreedma]

Well it was from memory from bigshot's rhetoric that's now been linked above of the 6S (and with more loads, Ken says it's good with the slight roll off being good and could sound warm). So another argument about headphone stage instead of DAC. I'm also into photography and I know that Ken Rockwell is not much of a source for accurate information (I once actually informed him about why extended ISO doesn't have better DR).

The “slight roll off” is less than .1db in the linked measurements. That isn’t audible. The quote from the site is: “Yes, it rolls off a tiny bit at the top, but that won't be audible. If it was, it would make it sound slightly smoother and warmer.” I’ll give you the benefit of the doubt that your misrepresentation of the quote was accidental.

 

[Jaywalk3r]

So are you also claiming every device sounds the same?

I'm saying that no one has provided any credible evidence supporting claims that there are audible differences among in-spec DACs currently offered.

My assertion has been that audible differences aren't just with DACs (and what we often hear is the different stages)...but if you believe it is hard to detect audible differences with all devices, then that's a different matter.

I invite you to provide evidence of that assertion. Until such evidence is presented, I'll assume your conclusion is based on cognitive biases, not actual differences. Similar claimed differences have disappeared when proper comparisons are performed. You'll be something of a rock star in audiophile circles if you could support your assertion with data.