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ODAC made all my Headamps Redundant ! - Page 2

post #16 of 24

Another thing to add is contrary to common belief, an amplifier doesn't always "amplify" the signal therefore your logic is a bit wrong.


I can fully understand your viewpoint. "It's already loud enough, why would I want to make it louder?"


Therefore, very simplified consider an amplifier as a "regulator" of both voltage/current to be able to drive different loads (headphones) without distortion.

post #17 of 24

when is this 'low impedance headphones are easier to drive' fallacy going to be replaced with fact? what makes low impedance headphones sometimes easier to drive is is they are high efficiency/sensitivity, nothing to do with impedance, it just so happens that many low impedance headphones are also very efficient. low impedance headphones vs high impedance headphones of the same efficiency are going to be HARDER to drive, not easier.


you will almost certainly be exceeding the voltage compliance of the dac at some frequencies as well as all the frequency response non-linearities that come with driving low impedance headphones with a highish output impedance, accentuated by the low voltage and low current capability of the chip.

Edited by qusp - 8/8/12 at 7:53am
post #18 of 24
Originally Posted by willmax View Post

For instance when I have the computer volume maxed out I can listen to Foobar at around 10 o'clock and it is plenty, and if I put Foobar volume beyond 12 it is too much. Let me know if anyone has had a similar experience and whether I should still try to use a amp or not.




If you lower the volume out in Windows/MacOS or in the audio player you're using, you're lowering the dynamic range that reaches your DAC... Not a good idea. People rave about 24 bit etc... But unfortunately far too many do stuff like what you just mentioned. Lessen the signal that reaches the DAC. Doesn't matter if it's 16 bit or 24 bit (which is already a much larger dynamic range than the hair cells in the ears can handle) if you're actually feeding it 12 bit or 10 bit, because you're scaling down the output to the DAC.


Someone else please elaborate if I'm unclear.

post #19 of 24

fun fact, lowering volume lowers DNR whether you do it analogue or digital. with high bit depth controls like the 40 bit of ESS, 64bit floating point of amarra, puremusic etc you are doing far less damage than with an analogue control. At least with digital you have perfect channel matching all the way through the range, this is especially useful and beneficial for balanced systems THD. sure the noise level does not scale and stays constant wrt the input signal with digital (lowers SNR), but this should be of zero consequence with any high quality modern dac.


eventually people will catch on to the fact that your average quality pot does more damage these days.

Edited by qusp - 8/8/12 at 9:16am
post #20 of 24

A 24 bit DAC playing back 16-bit source material does not reduce dynamic range but does

have a channel-balance better than 0.05 dB, no matter what-o'clock the volume-dial shows ..

It even beats stepped attenuators  !

post #21 of 24

its not a perfect world, digital attenuation does have penalties even with 24 and 32bit dacs as it shifts the bits over, very minor if you have your system well matched and the advantages far outweigh them IMO, but they are there. dont believe the hype. it WILL theoretically only start to increase distortion and noise if you have to attenuate more than say 24db, but in reality this likely starts a bit earlier and thats only if your player software actually does things right.


So basically if you have set up your gain structure well so that you listen with the volume turned up without blowing your eardrums then the penalty will be low, but if you also have several pairs of cans and some you need to attenuate heavily, you will be eating into SNR and in general screwing with linearity


of course 32bit dacs (some with 40+ bit volume) will handle this much better, even those however require you to think about gain structure. thats not something that is unique to digital attenuation though

Edited by qusp - 8/8/12 at 11:39am
post #22 of 24

in other words, its never a good idea to have more gain than you need in your amp stage

post #23 of 24
The ODAC doesn't have a volume knob. I'm wondering if the OP is actually talking about an O2/ODAC combo.
post #24 of 24
Originally Posted by lorriman View Post

The ODAC doesn't have a volume knob. I'm wondering if the OP is actually talking about an O2/ODAC combo.

You can still ajust volume with your media player .

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