[Tympan]

If you are hearing differences, I would ask you...

1) Are you carefully line level matching?
2) Are you patching through a preamp that allows instant direct A/B comparison?
3) Are you comparing line out (not headphone out) so it isn't just a simple impedance mismatch with your headphones?
3) Are you testing blind?

If the answer to any of those questions is no, I'm betting your results aren't correct. Reasonably well designed players should be audibly transparent. If they aren't, they are probably broken.

The only way to know for yourself for sure is to do a controlled test. I've done that dozens of time with the equipment I've bought over the years. I know,

 
I missed that part earlier.  
I agree there is always the possibility of mismatch impedance with iems/headphones and you are quite right about reminding to use the "line out" instead of "headphones out" when testing with a preamplifier. That is the only way to do it right without having two preamps in the chain and gain mismatch...
 
But in the case of iPhones, there is no line out (Headphones out only) = iPhone were designed to deliver sound to headphones and iems. As such, I think most people wondering about sound differences would assume the comparison was conducted with iem/headphones rather than with a preamplifier... and then maybe with an external portable amplifier... 
 
Anyway, the IP4 sounds fairly transparent and I am very happy with it. I will not upgrade until the next iPhone sound signature combines the technicality of the iP5 with the organic signature of the iP4, that's all.

 

[Roly1650]

Did he measure with any load.  Also, headphones?

4, is not near zero output impedance.  If multi BA headphones is 16 ohms, 4 is significant

If you want near zero, check out DX90.

Did  you see any square wave test?

Sorry, I don't wish to be rude, but rather than me transmit info, why don't you use the link I gave and go read the complete review yourself?
He does explain the output impedance and compares it to other headphone amps and in context of some headphones, but as I've already said, go look for yourself, it's fairly comprehensive........

 

[SilverEars]

Sorry, I don't wish to be rude, but rather than me transmit info, why don't you use the link I gave and go read the complete review yourself?
He does explain the output impedance and compares it to other headphone amps and in context of some headphones, but as I've already said, go look for yourself, it's fairly comprehensive........

 

[SilverEars]

At no load, they are all flat, and his first flat response was at 200Kohm load which should be flat for all. As the load get lower, it starts to distort.  His lowest he tested is at 32.

 

[SilverEars]

clip+
 

 

[bigshot]

  The iP5 is just MORE transparent

 
Wow! More inaudible than inaudible! That is a real trick! That tickles my funny bone!

 

[bigshot]

Psst! Silverears!
 
check out the range of the scale on the left hand side!

 

[SilverEars]

  Psst! Silverears!
 
check out the range of the scale on the left hand side!

I see it, Clip+ is totally flat at 16.

 

[bigshot]

Both the response curves you posted are stone flat. One of them has grid lines a half dB apart and the other is blown way up to .2dB divisions. Blow the .5 one up to the same scale as the .2 one and they might look identical. In any case, neither of them are anything but flat for human ears. One isn't better than the other in any meaningful way. They are both transparent when it comes to frequency response.

 

[Roly1650]

Psst! Silverears!

check out the range of the scale on the left hand side!

Took the words right out of my mouth or keyboard !!!!

At no load, they are all flat, and his first flat response was at 200Kohm load which should be flat for all. As he get lower, it starts to distort.  His lowest he tested is at 32.

Distortion? The graphs are showing frequency response........

 

[SilverEars]

Also to add, multi BA iems have crossovers, which includes resistors in the network.  4.5 output impedance will mess up the frequency range each driver would output.  32 ohm dynamic at load is not a good indicator of how multi BA iems would do.  

 

[bigshot]

The fact that IEMs require amping doesn't mean that there is something wrong with the output of the iPhone. Are you trying to pick and choose specs to prove the iPhone sucks or something? Because it doesn't make any sense. (And that isn't a good habit to get into.)

 

[SilverEars]

  The fact that IEMs require amping doesn't mean that there is something wrong with the output of the iPhone. Are you trying to pick and choose specs to prove the iPhone sucks or something? Because it doesn't make any sense. (And that isn't a good habit to get into.)

Actually, i'm pointing out that you can get the same specs with other players.  Samsung Galaxy S4 has pretty much the same specs with lower output impedance of 1.2 ohms.  iphone 4 was less than 1ohm.  It's nothing new.  These graphs don't tell you how well the headphones will perform with them.  I've looked at DX90, X5 graphs, they are all flat.  SS portables have lower than audible distortion, low output impedance.  
 
iems do not require amping, I'm talking about BA iems, not dynamic.  For multi BA iems, low output impedance is desired.  For example DX90 is less than <.1.   Amp is useful if the output has high impedance or if the the headphones are not as sensitive. 
 
Also, the power output graph does not tell you how the headphones will output with the input power.

 

[bigshot]

I don't think you're going to get much argument in Sound Science by saying that DAPs are audibly transparent. Unless there is something seriously wrong with their design and manufacture, that's certainly true. The same goes for CD players, SACD players and blu-ray players. Most computers intended for use as music sources as well. All players should be able to perform well enough that they are audibly transparent. When you can go out and buy a $40 cheapo DVD player and it performs to those specs, it isn't out of line to expect that from a fancy DAP designed specifically for listening to music.
 
As for headphone impedance matching... that is something you are going to need to pay attention to when you buy headphones. Some headphones require amping to perform properly and some don't. But that is irrelevant, because the measure of a player itself is usually made through line out, not the headphone out. The line out shows what the player itself is capable of. Matching with headphones depends on the headphones.

 

[Tympan]

There's a good review of the audio performance of the iPhone 5 at: kenrockwell.com. He used a $50k Rhode & Swartz audio analyzer for the test. His conclusion was that idevices including pods, pad and phones, all sound the same because they pretty much all measure the same and are transparent. That is they have performance beyond the range of human hearing to resolve differences. As he put it these devices have performance better than a high percentage of the audiophile "fluff", including stand alone dacs and headphone amps. For example he measured a s/n ratio of above 105dB, which indicates well above 16 bit performance.

A quote from his review: There isn't much difference between different iPods, iPhones and iPads; all pretty much have ultraflat response, near-zero output impedances and deliver 1 V RMS full-scale. People who hear huge differences in bass or treble aren't comparing them competently, or are comparing the internal speakers or something else.

 
1>
I'm always wary of "good reviews" saying such inconsistent things as "...all devises sound the same... ... there isn't much difference..." 
Either they sound the same and there isn't any difference (at all) or there isn't much difference and they don't sound the same. 
 
2>
When was this review written?  If the machine says numbers are too close between a 2004 nano and a 2014 iP5 for anyone to tell the difference, not only this 50K audio Analyzer is as useless as a toaster but the experiment itself is highly incompetent, which may explain why Mr Kenrockwell is trying to sell it for 10K (!!!) Hopefully, his review is just a bit dusty...