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Line-out & DAC/Pre-amp out, what's the difference?

post #1 of 11
8/27/08 at 1:50pm
Thread Starter 
I'm seeing on some DACs that there's not only a set of line-out jacks, but also DAC-out or pre-amp out jacks. What's the difference between these two, especially when hooking it up to a dedicated headphone amp?
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post #2 of 11
8/27/08 at 2:12pm
Quote:
Originally Posted by robojack View Post
I'm seeing on some DACs that there's not only a set of line-out jacks, but also DAC-out or pre-amp out jacks. What's the difference between these two, especially when hooking it up to a dedicated headphone amp?
Line out is *normally* a fixed voltage signal unaffected by the volume control. Pre-out is normally a variable signal since it is intended to be connected to a power amp, in this case adjusting the volume control adjusts the output signal level as a power amp is traditionally fixed gain.
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post #3 of 11
8/27/08 at 2:17pm
Line out will come directly from the DAC and fixed in volume level. If the DAC has a pre-amp out then the DAC has some sort of volume control capability, the DAC can essentially be used as a "preamp" with say an amp or even a powered subwoofer. If you already have a headphone amp you will want to use the regular old line out. If you were to use the pre-amp out then you would have two volume controls in the signal path which isn't needed and it's more "stuff" in the signal path which could degrade the sound. Hope this helps.

EDIT - oops, Nick beat me to it.
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post #4 of 11
8/27/08 at 2:53pm
Thread Starter 
Those are both superb explanations. Thank you both!
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post #5 of 11
9/1/08 at 12:57am
Hi

I have a Beresford DAC with variable and fixed outputs.

I like the gain on 10 with my Little Dot Mk3 but the Beresford has too much gain for the LD and my cans. I use the variable output from my DAC into my LDMk3 to match gain of the the 2 sources for my low impedance ATH-AD900's.
If I use the fixed output I have to turn the volume on the LD down to about 8 o'clock position where I get some channel imbalance and deterioration in SQ.

The LD runs best around 10- 12 o'clock setting and doesn't get too warm so I use the variable ouptut on the DAC to attentuate the gain into the LD. This way I have both settings around 10-12 o'clock and adjust the DAC if needed.
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post #6 of 11
1/27/11 at 11:23pm

"Necro" bumping this thread...for a simple question...

 

Since pre-amp/dac out's only difference compared to line-out is in the adjustability, would this mean I can just use the pre-amp output as the lineout to connect to another amplifier? for the maximum SQ, do I turn the volume pot up all the way?

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post #7 of 11
8/16/11 at 10:19am

Bump...

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post #8 of 11
8/16/11 at 10:20am
Quote:
Originally Posted by juman231 View Post

"Necro" bumping this thread...for a simple question...

 

Since pre-amp/dac out's only difference compared to line-out is in the adjustability, would this mean I can just use the pre-amp output as the lineout to connect to another amplifier? for the maximum SQ, do I turn the volume pot up all the way?


Bump...

 

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post #9 of 11
8/16/11 at 10:21am

...

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post #10 of 11
8/16/11 at 10:54am
Quote:
Originally Posted by juman231 View Post

"Necro" bumping this thread...for a simple question...

 

Since pre-amp/dac out's only difference compared to line-out is in the adjustability...

 

Another difference is SQ (sound quality).  With each additional component that you add, you also add the possibility of degrading the sound- or at least altering it.  That's why if your amplifier has a volume of its own, use the fixed line out on your DAC.  Otherwise, you're sending the audio signal through two volume devices instead of one.
 

Quote:
for the maximum SQ, do I turn the volume pot up all the way?

 

If you are using a variable out (once in a while you don't have a choice- it may be all there is), then typically you would want to set the volume in the earliest device (source) to the maximum level.  On occasion that maximum level might be too high for the 'next' component down; which means you will want to adjust the level a bit lower.  In other words, set the level as high as you can go before clipping occurs.  Hope this helps!

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post #11 of 11
8/16/11 at 6:23pm

It's going to depend upon the specific unit. While it's true that a pre-amp adds another stage, and thus potential for noise or distortion, it's also likely to have more power behind it. Depending upon what the next stage is (and maybe even how long the cable is), this might or might not matter. Most likely there won't be a difference.

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