Line-out - Headphone-out + amp confusion

[Ttvetjanu]

I've been looking around the forums for quite a while at different Mp3 players and I have always had the impression that the line-out sound is 'purer' and better than the headphone out sound because it bypasses the cheap internal amplifier which you can find inside the players. Therefore I have also been under the impression that you should always connect a headphone amplifier into the line-out if possible (of course to use the line-out you also need an amplifier).

Now, however, I'm a bit confused. As I have been reading more and more it doesnt seem to be that simple. Most players don't have line-outs so you have to connect docks/mod them etc. and even then the sound quality might not be as good as another players headphone-out. Also it is generally not even possible to get the line-out sound from most players.

To be more specific, are there players that have a better sound quality from their headphone-out than an 5g ipod has from its dock/line-out? What will happen to the sound quality if you amplify the headphone-out instead of a line-out? Wont the garbage in garbage out concept only make the cheap chip inside the player more amplified and the sound even worse? I myself have been looking around at players that have flash 4-8gb with a decent video playing screen (new nano/mini?) e.g. the Zen, Meizu M6, iAudio D2 etc. Would waiting for the new ipods pay off as you would probably be able to get the line-out.

At the moment I am waiting for my c&c box+ to arrive and as portable sources i have a 1g and 2g shuffle aswell as a decent cd-player (with line-out).

 

[tot]

Quote:

Originally Posted by Ttvetjanu /img/forum/go_quote.gif What will happen to the sound quality if you amplify the headphone-out instead of a line-out? Wont the garbage in garbage out concept only make the cheap chip inside the player more amplified and the sound even worse?

Since I don't have a player with line-out I tried my Samsung YP-Z5 headphone out to HR Micro Amp and Shure E500. It sounded better, less harsh and bit more bass than the player itself, but I decided the difference is too small to bother with amp and loose the convenience of a small player.

Line-out needs an amplifier too, but since the impedance is high (10kR or so) it needs to supply very little current. I guess that's why the headphone-out works better when connected to an amp instead of headphones too, but it has not been designed for that like the line-out is.

 

[Andrew Jones]

Have a look at this post:
http://www.head-fi.org/forums/showpo...2&postcount=16

 

[Assorted]

I think "bypassing the internal amp" is a concept that came with the iMod.

I amp my headphone out from my DAP and there's noticeable difference, especially with my 650s.

 

[epaludo]

When you connect the headphone output from a DAP to an external amp, the signal is beeing amplified twice. One by the DAP's internal amp and other by the external amp. It's not recommended to amplify the signal twice, once it'll probably add some not desired distortion.

I've also noticed that connecting a headphone output to an external amp can improve the sound, but connecting a line-out can improve a lot more ...

 

[silmaauki]

Quote:

Originally Posted by epaludo /img/forum/go_quote.gif When you connect the headphone output from a DAP to an external amp, the signal is beeing amplified twice. One by the DAP's internal amp and other by the external amp. It's not recommended to amplify the signal twice, once it'll probably add some not desired distortion. I've also noticed that connecting a headphone output to an external amp can improve the sound, but connecting a line-out can improve a lot more ...

Did you read the post that Andrew Jones linked?

You should.

I quess that in all (most?) cases when there's a line out in DAP this line out uses mostly the same (amplifying) circuit as the headphone amp. In some cases the line-out is just a fixed volume setting (of the headphone out) and in some cases the line-out uses slightly different gain setting.

Anyhow, another issue is the quality of the (amplifying) circuitry. Not to mention the "good fit" with the rest of the stuff used. Life is not too simple.

Besides, if you want to have a setup where the amlifying is done only once, then you must look for a good headphone out. Note: This is a "bad example", not my opinion!

 

[Tone Def]

But with the headphone out you still have to find the zero gain volume level by trial and error as opposed to using a dock where you're sure you've found it.

 

[jinp6301]

Quote:

Originally Posted by Tone Def /img/forum/go_quote.gif But with the headphone out you still have to find the zero gain volume level by trial and error as opposed to using a dock where you're sure you've found it.

you can measure it by a multimeter (i might be wrong on this one)

 

[Tone Def]

Eh? You learn something everyday! lol

 

[silmaauki]

I think there is a kind of missunderstanding somewhere.

I haven't said that headphone out is better that line out. I have tried to raise the question about validity of "line out is better that headphone out" -statement.

I would say that in most cases when there are both line-out and headphone out the quality of theses outputs are usually the same. At a certain volume setting they can be technically equal. Of course these outputs could be technically very different. My current understanding is that this is not usually the case.

If my DAP would have a line-out, propably I would be using it for headphone amp. At least it would be easier to have only one volume pot in use.

 

[Assorted]

I'm a bit confused about the referenced post. Doesn't "gain" mean to add volume?

For example my Sony NW-HD1 has a headphone out and line out function. When it's using line-out, it's just as loud as the loudest on headphone out. So if an internal amplifier "gains" the line-level signal, is it effectively "lowering" the volume? Wouldn't that defeat the purpose of being an "amplifier"?

 

[tot]

Quote:

Originally Posted by Assorted /img/forum/go_quote.gif I'm a bit confused about the referenced post. Doesn't "gain" mean to add volume? For example my Sony NW-HD1 has a headphone out and line out function. When it's using line-out, it's just as loud as the loudest on headphone out. So if an internal amplifier "gains" the line-level signal, is it effectively "lowering" the volume? Wouldn't that defeat the purpose of being an "amplifier"?

The internal amplifier produces the line level signal, about 2V max. Since that voltage is quite loud for low-impedance headphones, the volume control only attenuates the signal for headphone-out. No need for two amplifiers inside a small box and no need to "gain" the line level signal.

To drive a higher impedance phones you would need to gain the line-level signal to higher voltage to get enough power for the headphone drivers.