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Relationship between Source and DAC?

post #1 of 13
Thread Starter 

Hi,

 

This maybe a stupid question but here goes....

 

If you use an iPhone/Ipod connected to a DAC via a LOD cable thus bypassing the internal DAC,  would the sound quality out of the outboard DAC be the same as if any source was being used to feed the DAC be it a computer or another mp3 player etc?

 

Hope that makes sense.

 

Thanks

 

Si

post #2 of 13
In theory, yes. In reality, I would be inclined to think a mobile device would have a dirtier line. However, I don't think you'd be able to hear the difference.

You could use a digital oscilloscope to check.
post #3 of 13
Quote:
Originally Posted by snootles View Post
 

Hi,

 

This maybe a stupid question but here goes....

 

If you use an iPhone/Ipod connected to a DAC via a LOD cable thus bypassing the internal DAC,  would the sound quality out of the outboard DAC be the same as if any source was being used to feed the DAC be it a computer or another mp3 player etc?

 

Hope that makes sense.

 

Thanks

 

Si

 

A normal LOD does not bypass the internal DAC, to do this you need a specialized dock with an Apple licensed (and thus expensive) chip in it. So you are looking at about $200 - $300 to do this i.e  

http://www.amazon.com/Cambridge-Audio-iD100-Digital-Black/dp/B004KSKYUE/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1385488242&sr=1-1-catcorr&keywords=iD100+Digital+Dock

 

a normal LOD will just give a you a fixed line level analog signal. That said the internal DAC of most iPods are pretty good and you can happily feed the output to an amp/speakers and get good sounds


Edited by nick_charles - 11/26/13 at 9:54am
post #4 of 13
Thread Starter 

So as long as you use a dock that bypasses the internal DAC like a Pure I-20 then the sound quality should be the same no matter the source as it's the Dac and Headamp that are doing the work?

post #5 of 13

I personally believe the internal DAC in the current gen iPod (classic) is as close to perfect as we are going to find in a portable product, and don't see the need to spend so much money to bypass it.

 

If it's not broken, why fix it?

 

(@bigshot ?)


Edited by White Lotus - 11/26/13 at 9:26pm
post #6 of 13
Thread Starter 
Quote:
Originally Posted by White Lotus View Post
 

I personally believe the internal DAC in the current gen iPod (classic) is as close to perfect as we are going to find in a portable product, and don't see the need to spend so much money to bypass it.

 

If it's not broken, why fix it?

 

(@bigshot ?)


For portable use I agree but from a purely technical point of view, if the idevice is used as the main source in a home setup into a dac, bypassing the internal dac, the sound should be the same out of the external dac as it would be using a pc/mac for example. Is the right or wrong?

post #7 of 13
Quote:
Originally Posted by snootles View Post
 


For portable use I agree but from a purely technical point of view, if the idevice is used as the main source in a home setup into a dac, bypassing the internal dac, the sound should be the same out of the external dac as it would be using a pc/mac for example. Is the right or wrong?

Technically yes, but you can also expand the question (as we are prone to  do here). To link an Ipod that has a pretty decent DAC to a 2nd DAC requires not only the 2nd DAC (which the OP may already have) but also a $200 - $300 gizmo to overcome the egregious Apple licensing and (arguably) short-sighted design decisions to get to the state where you get an output signal that is louder than the Apple Line out but maybe not really noticeably better in other terms. There was a famous CES demo where Wilson demo'ed some of their big-arse speakers using an iPod hidden in the shell of a $20K CD player, not one listener complained about the sound being substandard.

post #8 of 13
Quote:
Originally Posted by snootles View Post
 


For portable use I agree but from a purely technical point of view, if the idevice is used as the main source in a home setup into a dac, bypassing the internal dac, the sound should be the same out of the external dac as it would be using a pc/mac for example. Is the right or wrong?

 

using the exact same DAC (whether bypassing it from the ipod or coming from a computer) will get you exactly the same response regardless of source.  so yes, you are right not wrong in your statement.  the only caveat is that your source isn't doing something to the audio chain before the DAC (DSP, EQ, etc.).  i've been led to believe that the LOD will bypass the internal DSP/EQ/AMP on an ipod and just pass through the DAC, if there is proof out there that this is not the case i'd love to see it.

post #9 of 13

Similarly, if I use an external USB DAC with my computer, is it supposed to bypass my laptop's pre-amp/EQ settings or just the DAC (soundcard)? And if I decide to EQ/Pre-amp directly from ITunes built-in functions, I guess it does affect the sound because it is at the very source?

post #10 of 13

Yes. If you do signal processing in the audio player, then changing the sound card/interface/DAC won't change the processing, but if you did the processing in your soundcard's control panel / driver, then it will change.

post #11 of 13
Quote:
Originally Posted by White Lotus View Post
 

I personally believe the internal DAC in the current gen iPod (classic) is as close to perfect as we are going to find in a portable product, and don't see the need to spend so much money to bypass it.

 

If it's not broken, why fix it?

 

(@bigshot ?)

  

This.

post #12 of 13

Doesn't that depend on your sound card?

post #13 of 13

@callmenowla: That's exactly what I wrote a week ago.

 

@bigshot: Sure, some beats audio stuff for example forces its processing on the user. Other soundcards have configurable EQ, reverb effects, ... and many USB DACs just come with a bare minimum driver without such features.

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