[castleofargh]

 ​

 ​

This topic is my attempt at answering that question without having to rocket science so that my mother can get a meaning out of it. and hopefully you guys too.​

Spoiler: You're not deaf, and I'm not a golden ear.(well that's a bummer)

 
I measured the volume level out of 2 DAPs in different situations using trueRTA(free software). I could have used something much more detailed like a fancy spectrum of the frequency response, or RMAA the DAPs(well I did, if at some point it feels relevant, but I don't think it is for the subject).  or I could have simplified to the extreme with a simple VU meter. I thought this was good enough to show my point about hiss and why some get it and other think they don't.

 
So here is one of my DAPs playing a 1khz tone plugged back to the computer through a focusrite. Nothing high end, nothing is fully calibrated(the 0db signal is set at 0.35v,  far from testing ideal fullscale stuff), as all I want is to show changes, I only took care of keeping everything identical and thus set things up for the worst device in the worst situation. and that's about it. I'm a noob with noob gears.

​

 
 
 

 
let me sing you the song of my people!
You can clearly see(if you click on the picture...) my nice 1khz test tone reaching -3db, that's the “music” I'm playing(because I'm an objectivist I only have playlists of test tones, like all subjectivist can tell you), and the next thing is way below at almost -78db. So if I think of it as listening to music, I would have my music at normal loudness up there, and all the crap that isn't music, would be at least 78db quieter, as good as non existent when it comes to hearing it.
but that's with my DAP set very loud compared to what I use with my IEMs, and plugged directly into the recording device so the DAP has an easy job of driving the load.  So this is in no way a realistic situation. :'(
 
 
 
 

 
Here is a more realistic situation, that's the loudness I really set when listening to music with my 300ohm IEMs etyKids
 

 
Playing the 1khz tone shows to be -47db loud. Compared to the more flattering graph before, the crap in the trebles didn't really go down with the music, so now it's like the garbage is closer. With the treble crap reaching -81.39db that means I got crap sound only 81.39-47=34.39db below my music.

We don't know where it is, maybe the noise is a single point at 19khz and I wouldn't notice it if it was as loud as the music(my hearing is ok up to 16.5khz). But still it's coming dangerously close to the playing music and looks bad when we put it in perspective with the high resolution DAP marketing propaganda.

 
 
 
 
In this graphs I have now set the DAP at the loudness I usually use when listening to my IE80 . they are very sensitive IEMs and when I notice some background noise on a DAP it's often with those:


Because the IE80 are more sensitive than the etyKid IEM, to get the same perceived loudness in my ears, I need to lower the volume level of my DAP. logic!
but what if some of the background noise doesn't go down with the volume level like on the very DAP I used up till now? then it's like the noise is louder again.
The 1khz "music" in my example is now 63-47= about 16db quieter, and it sounds like the background noise is 16db louder in my ears because of the IE80's higher sensitivity. 10db louder feels like double the loudness, so no wonder I notice background noises a lot more on the IE80 than on the etyKids. the background crap is now real close to my music.

 
And there you have it, we could use the same DAP, but simply because you're not using an IEM as sensitive as mine, you may never get bothered by any form of hiss in the background of your music.
And that why some notice a hiss and some don't, as simple as that. it's only a matter of how sensitive your IEM can be. so the obvious solution against a DAP that hisses is to avoid buying very sensitive IEMs!

 
 
 
 
You can now stop reading and complain that I wasted your time with a badly done experiment, the original question has been answered with concrete visual example.
Or if you really have nothing to do because your torrent didn't finish downloading, then you can stay, it's free:

 
The graphs below are to show how from one DAP to another the noise floor might not be the same, and why I often use an external amp not for power, but to clear up the background a little.

 here is another DAP, this time with a 8ohm resistor to simulate the load(it was just too clean without the 8ohm load ^_^), so I'm not being nice with that poor DAP. But nowadays many high end IEMs can go as low as 8ohm, and the 20 or 30ohm written on the specs are only the impedance at 1khz.
You can see there is crap everywhere, but rather low, so that's a pretty nice result for a consumer DAP.

 
Now another DAP that doesn't take the 8ohm in with the same dignity:

for the same output setting, you see the 4khz(remember I'm only using a 1Khz test tone, there is no music at 4khz) is about 10db(feels twice as loud) louder than the noise from the previous DAP. and even though the low frequencies are super clean, I tell you I'm hearing a clear hiss on this one with my IE80 when it's more subtle using the previous DAP.
I call those stuff noise, but it could as well be harmonic distortions, I have no real way to know just measuring the amplitude of the signal like I did. but whatever it is, if I can hear it, it's garbage!

 
So with some IEMs, that DAP hisses too much for me and I'm annoyed. and here is what I do, I plug in my external amp, and at least for this very dubious reading, it's not too hard to recognize progress:

 
 
 
I see external amps as a great solution for some noises, but don't get me wrong, to need a solution, you first need a problem. It's really no fun to carry a brick around if the DAP alone already sounds clean and has enough power for our IEM/headphone. and in some cases, the amp might just hiss more than the DAP.
 
 
 
 
 
and there you go, I hope some who didn't understand why people complain about hiss from a DAP, now understand why it can be real without them hearing any. and I also hope that it may give some practical solution to those who are annoyed by some hissing DAP. lower sensitivity IEM, or amp.

 

[Exacoustatowner]

 

 ​

 ​

This topic is my attempt at answering that question without having to rocket science so that my mother can get a meaning out of it. and hopefully you guys too.​

Spoiler: You're not deaf, and I'm not a golden ear.(well that's a bummer)

 
I measured the volume level out of 2 DAPs in different situations using trueRTA(free software). I could have used something much more detailed like a fancy spectrum of the frequency response, or RMAA the DAPs(well I did, if at some point it feels relevant, but I don't think it is for the subject).  or I could have simplified to the extreme with a simple VU meter. I thought this was good enough to show my point about hiss and why some get it and other think they don't.

 
So here is one of my DAPs playing a 1khz tone plugged back to the computer through a focusrite. Nothing high end, nothing is fully calibrated(the 0db signal is set at 0.35v,  far from testing ideal fullscale stuff), as all I want is to show changes, I only took care of keeping everything identical and thus set things up for the worst device in the worst situation. and that's about it. I'm a noob with noob gears.

​

 
 
 

 
let me sing you the song of my people!
You can clearly see(if you click on the picture...) my nice 1khz test tone reaching -3db, that's the “music” I'm playing(because I'm an objectivist I only have playlists of test tones, like all subjectivist can tell you), and the next thing is way below at almost -78db. So if I think of it as listening to music, I would have my music at normal loudness up there, and all the crap that isn't music, would be at least 78db quieter, as good as non existent when it comes to hearing it.
but that's with my DAP set very loud compared to what I use with my IEMs, and plugged directly into the recording device so the DAP has an easy job of driving the load.  So this is in no way a realistic situation. :'(
 
 
 
 

 
Here is a more realistic situation, that's the loudness I really set when listening to music with my 300ohm IEMs etyKids
 

 
Playing the 3khz tone shows to be -47db loud. Compared to the more flattering graph before, the crap in the trebles didn't really go down with the music, so now it's like the garbage is closer. With the treble crap reaching -81.39db that means I got crap sound only 81.39-47=34.39db below my music.

We don't know where it is, maybe the noise is a single point at 19khz and I wouldn't notice it if it was as loud as the music(my hearing is ok up to 16.5khz). But still it's coming dangerously close to the playing music and looks bad when we put it in perspective with the high resolution DAP marketing propaganda.

 
 
 
 
In this graphs I have now set the DAP at the loudness I usually use when listening to my IE80 . they are very sensitive IEMs and when I notice some background noise on a DAP it's often with those:


Because the IE80 are more sensitive than the etyKid IEM, to get the same perceived loudness in my ears, I need to lower the volume level of my DAP. logic!
but what if some of the background noise doesn't go down with the volume level like on the very DAP I used up till now? then it's like the noise is louder again.
The 1khz "music" in my example is now 63-47= about 16db quieter, and it sounds like the background noise is 16db louder in my ears because of the IE80's higher sensitivity. 10db louder feels like double the loudness, so no wonder I notice background noises a lot more on the IE80 than on the etyKids. the background crap is now real close to my music.

 
And there you have it, we could use the same DAP, but simply because you're not using an IEM as sensitive as mine, you may never get bothered by any form of hiss in the background of your music.
And that why some notice a hiss and some don't, as simple as that. it's only a matter of how sensitive your IEM can be. so the obvious solution against a DAP that hisses is to avoid buying very sensitive IEMs!

 
 
 
 
You can now stop reading and complain that I wasted your time with a badly done experiment, the original question has been answered with concrete visual example.
Or if you really have nothing to do because your torrent didn't finish downloading, then you can stay, it's free:

 
The graphs below are to show how from one DAP to another the noise floor might not be the same, and why I often use an external amp not for power, but to clear up the background a little.

 here is another DAP, this time with a 8ohm resistor to simulate the load(it was just too clean without the 8ohm load ^_^), so I'm not being nice with that poor DAP. But nowadays many high end IEMs can go as low as 8ohm, and the 20 or 30ohm written on the specs are only the impedance at 1khz.
You can see there is crap everywhere, but rather low, so that's a pretty nice result for a consumer DAP.

 
Now another DAP that doesn't take the 8ohm in with the same dignity:

for the same output setting, you see the 4khz(remember I'm only using a 1Khz test tone, there is no music at 4khz) is about 10db(feels twice as loud) louder than the noise from the previous DAP. and even though the low frequencies are super clean, I tell you I'm hearing a clear hiss on this one with my IE80 when it's more subtle using the previous DAP.
I call those stuff noise, but it could as well be harmonic distortions, I have no real way to know just measuring the amplitude of the signal like I did. but whatever it is, if I can hear it, it's garbage!

 
So with some IEMs, that DAP hisses too much for me and I'm annoyed. and here is what I do, I plug in my external amp, and at least for this very dubious reading, it's not too hard to recognize progress:

 
 
 
I see external amps as a great solution for some noises, but don't get me wrong, to need a solution, you first need a problem. It's really no fun to carry a brick around if the DAP alone already sounds clean and has enough power for our IEM/headphone. and in some cases, the amp might just hiss more than the DAP.
 
 
 
 
 
and there you go, I hope some who didn't understand why people complain about hiss from a DAP, now understand why it can be real without them hearing any. and I also hope that it may give some practical solution to those who are annoyed by some hissing DAP. lower sensitivity IEM, or amp.

Interesting! I may get a DAP soon-if I get the Oppo PM3's. I'm too tired to come up with any snappy comebacks-other than you mentioned you only have test tones- this PROVES you are a real Sound Scientist. I've only got a single test disc. I do enjoy listening to the 1 Khz sine and square waves!

 

[castleofargh]

I've stopped square waves, not my genre.

 

[Exacoustatowner]

  I've stopped square waves, not my genre.

I get nostalgic sometimes.

 

[Duncan]

This thread deserves at list one mini bump for an interesting discussion point...

It frustrates me that I can hear real world hiss when others with the same equipment cannot... Guess my 38yr old ears are just still sensitive enough to pick up on it (not bad with all the abuse I've given them over the years!!)

 

[castleofargh]

This thread deserves at list one mini bump for an interesting discussion point...

It frustrates me that I can hear real world hiss when others with the same equipment cannot... Guess my 38yr old ears are just still sensitive enough to pick up on it (not bad with all the abuse I've given them over the years!!)

thanks, it's a very crude way to show it and part of the noise floor I get in the trebles is from the recording part itself instead of the DAP. but it's the only way I came up with that didn't involve sensitivities and voltage examples that would not speak to people. at least with graphs it's not hard to see changes and imagine what they are.
 
but of course the kind of music, how loud we tend to listen to music, and how loud is the place we're in, those also directly impact the possibility of noticing background hiss.
I'm kind of locked onto the idea that it's pointless to run after hifi if there is a blanket of noise covering it all, so that turned me into a very noise obsessed guy.
when people thought I was mad talking about hiss they didn't get, for years I took comfort in reading shigzeo's reviews, knowing I wasn't alone ^_^. now I have this topic to try and explain that when someone doesn't hear it, I'm not saying he's half deaf(even though, he could be). 

 

[goodyfresh]

Nice thread, dude!  Very informative

 

[prot]

A nice & useful investigation indeed Naming those DAPs wont hurt.

 

[castleofargh]

A nice & useful investigation indeed Naming those DAPs wont hurt.

I wondered about that TBH. I felt that it would just end up with people pasting the graph as "proof" that dap X is crap. I've seen that kind of out of context post too many times already.
 
but at the same time it's not like I have a serious reason to hyde it. the one with rising crap was my sony A15, the one with even noise at all freqs was a Xduoo X2.  and in fact both are pretty noisy on senstive IEMs. 
I wished to measure my fiio X1 to show how improved the noise floor is, but the thing is, it was under the noise floor from my recording device

so no X1 for that post.
same thing with the leckerton amp, I ended up with results too low if I used anything but the noisy and weak(0.4v) LO of the A15. so I didn't fake anything, but I did go for worst case scenarios within the gears that I had at home, so that I could measure something.

 

[prot]

I wondered about that TBH. I felt that it would just end up with people pasting the graph as "proof" that dap X is crap. I've seen that kind of out of context post too many times already.

but at the same time it's not like I have a serious reason to hyde it. the one with rising crap was my sony A15, the one with even noise at all freqs was a Xduoo X2.  and in fact both are pretty noisy on senstive IEMs. 
I wished to measure my fiio X1 to show how improved the noise floor is, but the thing is, it was under the noise floor from my recording device :rolleyes: so no X1 for that post.
same thing with the leckerton amp, I ended up with results too low if I used anything but the noisy and weak(0.4v) LO of the A15. so I didn't fake anything, but I did go for worst case scenarios within the gears that I had at home, so that I could measure something.

That sounds a bit less useful. Guess it's expected that crappy DAPs sound kinda crappy .
Anyway, I'm a sucker for interesting measurements and always glad to see new aproaches.

 

[goodyfresh]

 
I wondered about that TBH. I felt that it would just end up with people pasting the graph as "proof" that dap X is crap. I've seen that kind of out of context post too many times already.
 
but at the same time it's not like I have a serious reason to hyde it. the one with rising crap was my sony A15, the one with even noise at all freqs was a Xduoo X2.  and in fact both are pretty noisy on senstive IEMs. 
I wished to measure my fiio X1 to show how improved the noise floor is, but the thing is, it was under the noise floor from my recording device

so no X1 for that post.
same thing with the leckerton amp, I ended up with results too low if I used anything but the noisy and weak(0.4v) LO of the A15. so I didn't fake anything, but I did go for worst case scenarios within the gears that I had at home, so that I could measure something.

That's interesting that you couldn't even manage to measure the noise-floor of the X1 since it was so low

 

[castleofargh]

@prot 
I know, at first I hoped to be able to do measurements of all my stuff under "real life" voltages with maybe 8 or 16ohm. as I find most measurements useless for the portable world. (no load, usually close to full output, who cares that a DAP is good under those conditions?), but I would clearly need a very good input that I don't have. using the scarlet 2i2 already is a great upgrade compared to my laptop mic input that gave me -35db of crosstalk and about -50db of distortions with everything I plugged into it ^_^.
 
I guess I can't improvise myself great measurement guy just with very average gears.
I thought of a way to go with using an amp and playing a silent track greatly boosted, but then I get the noise when plugged into high impedance, not real life stuff under low impedance load. so I'm a little stuck when it comes to measuring good stuff as I hoped to do.
 
 
@goodyfresh
yes the X1 is pretty clean. not dead clean, I can still get a little something when in perfect silence with the most sensitive IEM. my O2 and UHA760 are what I call dead silent. but that's paranoid level,  I'd be real surprise to hear anybody complain about the X1 hissing. most DAPs are noisier. but it does have 2ohm of output that could be a reason to avoid it with some IEMS. and that's not even considering the rest of sound qualities or UI or size....
hard to find the perfect DAP ^_^.

 

[goodyfresh]

  @goodyfresh
yes the X1 is pretty clean. not dead clean, I can still get a little something when in perfect silence with the most sensitive IEM. my O2 and UHA760 are what I call dead silent. but that's paranoid level,  I'd be real surprise to hear anybody complain about the X1 hissing. most DAPs are noisier. but it does have 2ohm of output that could be a reason to avoid it with some IEMS. and that's not even considering the rest of sound qualities or UI or size....
hard to find the perfect DAP ^_^.

I really enjoy my X3 2nd Generation I've never noticed any hiss from it with anything.  ANd in terms of sound-for-your-money, it can't be beat when it comes to value

  It was kinda glitchy occasionally for a while but Fiio just released a new firmware update that has fixed all the glitches/issues I ever seem to have had with it.

Also, it has a much lower output-impedance than the X1, something like 0.3ohms.  If I'm not mistaken, isn't the rule of thumb to always use something with an output-impedance at or below 1/8th that of the headphones or IEM's?  So for the X1, you wouldn't want to use anything at 15ohms or below, only stuff at 16 and up, right?

 

[prot]

It's not so hard/expensive to build a reasonably good measurement rig. E.g. a creative emu 404 for about $100 and the mic Dirac uses for another $100. Plus some free software.
Wanted to do it myself but I just cant find the time for such fun.

 

[castleofargh]

 

  @goodyfresh
yes the X1 is pretty clean. not dead clean, I can still get a little something when in perfect silence with the most sensitive IEM. my O2 and UHA760 are what I call dead silent. but that's paranoid level,  I'd be real surprise to hear anybody complain about the X1 hissing. most DAPs are noisier. but it does have 2ohm of output that could be a reason to avoid it with some IEMS. and that's not even considering the rest of sound qualities or UI or size....
hard to find the perfect DAP ^_^.

I really enjoy my X3 2nd Generation I've never noticed any hiss from it with anything.  ANd in terms of sound-for-your-money, it can't be beat when it comes to value

  It was kinda glitchy occasionally for a while but Fiio just released a new firmware update that has fixed all the glitches/issues I ever seem to have had with it.

Also, it has a much lower output-impedance than the X1, something like 0.3ohms.  If I'm not mistaken, isn't the rule of thumb to always use something with an output-impedance at or below 1/8th that of the headphones or IEM's?  So for the X1, you wouldn't want to use anything at 15ohms or below, only stuff at 16 and up, right?

the 1/8 rule is kind of an all in one thing. not specifically for signal quality, but also for power efficiency, and to make sure you limit frequency variations when the IEM/headphone doesn't have a flat impedance response over frequencies.
 but yeah it's really never a bad idea to follow it. I didn't get to hear the X3II but the first X3 was also a model of clean output. didn't sound really neutral IMO but the background really impressed me at the time.
 

It's not so hard/expensive to build a reasonably good measurement rig. E.g. a creative emu 404 for about $100 and the mic Dirac uses for another $100. Plus some free software.
Wanted to do it myself but I just cant find the time for such fun.

well I did read a lot without knowing anything(not a musician) and bought a scarlet 2i2 instead of a EMU. good choice or bad choice IDK.
 
I got a bunch of resistors so that I can measure the output with a load(for RMAA and stuff), I have 2 cheap mics if I want to record the output of an IEM. all that is great for the price and I really enjoy experimenting some things myself instead of reading conflictual crap on the web. but unless I'm doing something wrong,  when the source is pretty clean, some of the numbers I get seem to be the scarlet's instead of the source. and noise would be one of those.