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Double Amplification

post #1 of 11
Thread Starter 
i am using iBasso D2 Boa as DAC..even though it doesnt have line out.

and then i connected it to the Crossroads Edge amp via 3.5 mm to RCA cable.

and put Edge amp on high gain
am i doing anything wrong?
i turn the volume knob on boa to 75%
and Edge amp is variable.


anything wrong with Double amplification? ..is there a proper way to do it?
post #2 of 11
I've always wondered the same thing.

From what I understand though. Seems like unless you really need a double amplification or a preamp, you shouldn't do it. Some people (including me) believe that the more links you add to a chain the more risk the SQ could degrade.
post #3 of 11
Quote:
Originally Posted by Lamenthe View Post
I've always wondered the same thing.

From what I understand though. Seems like unless you really need a double amplification or a preamp, you shouldn't do it. Some people (including me) believe that the more links you add to a chain the more risk the SQ could degrade.
Any time you amplify the output of a DAP you are doing this. Since each amp section will have its own noise ratio and the noise is additive, however if the amps sections are both decent the degradation should be minimal.

I have tested line-out vs headphone out amping on my iPod and (at least through speakers) the extra added noise is not really noticeable.

Though I feel an elaborate loop-back recording DBT coming on when I have finished my cable tests...
post #4 of 11
This is probably fine - basically all integrated receivers are doing 'double amplification' (once in the preamp stage, again in the amplifier stage).

I think you're right to set the second amplifier to lowest attenuation and then use the first amplifier as the volume control. If you're using middle values of both volume controls, you're picking up the noise of both pots.
post #5 of 11
Quote:
Originally Posted by nick_charles View Post
Any time you amplify the output of a DAP you are doing this. Since each amp section will have its own noise ratio and the noise is additive, however if the amps sections are both decent the degradation should be minimal.

I have tested line-out vs headphone out amping on my iPod and (at least through speakers) the extra added noise is not really noticeable.

Though I feel an elaborate loop-back recording DBT coming on when I have finished my cable tests...
That's what I mean, but you said it in a lot greater detail. It's true it's a minimal issue as long as you have good components. I was just saying as an audiophile less is more . This is audiophile territory here, people spend hundreds to thousands on an extremely minimal increase in clean output.

Good to hear some feedback on the matter though (even if I'm not the OP). I'm just really curious about optimizing Amp/DAC -> Amp too. I'll be taking notes once more people reply.
post #6 of 11
Quote:
Originally Posted by MoodySteve View Post
This is probably fine - basically all integrated receivers are doing 'double amplification' (once in the preamp stage, again in the amplifier stage).
This really isn't the same thing. The concept is the same in very rough terms, but in reality the implementation here is very different.

Quote:
Originally Posted by nick_charles View Post
I have tested line-out vs headphone out amping on my iPod and (at least through speakers) the extra added noise is not really noticeable.
I have done the same comparison with my iPod nano, and Classic and found the difference surprisingly significant; specifically the additional noise. Line out produced far less noise in my experience (especially noticeable through IEMs in my case). In fact for me, the difference in extra noise alone via headphone out was convincing enough to keep my Pico and always use line out of my iPods.

Double amplification as a general rule, is a bad idea. You are adding noise and distorting the quality of the audio you would otherwise experience. A simple test is to turn on your gear as you normally would without playing music and crank the volume up. All being well you will hear perfect silence, but chances are you might hear some static or buzz - that's the noise you're adding to your system.

However... there are other factors to consider. Most notable is that if it sounds good, and you can't really hear any noise, buzzing or interference... enjoy the music. I presume (apologies if I'm wrong), that the OP's setup is due to financial constraints or for practical reasons - nothing wrong with that! If all components in the chain are of good quality, and interconnects are short, shielded and properly terminated, chances are any unwanted noise will be insignificant.
post #7 of 11
Thread Starter 
i have done lot of trial n error..and noticed if u use the volume knobs properly u can vastly minimize any noise or distortion.
in ipod case..the jack itself sux..atleast boa is a much better out to begin with.

any more people using double amping with success here?
post #8 of 11
Quote:
Originally Posted by poo View Post
This really isn't the same thing. The concept is the same in very rough terms, but in reality the implementation here is very different.
Please explain how the implementation is 'very different' and only similar in 'very rough terms' between connecting the preamp and amp stages in a single chassis versus connecting them in two separate chassis (not being inflammatory - if I'm missing something here I do want to know )

It seems to me that the Boa is a headphone amp and thus very likely a good preamp (low noise, low output impedance). In the OPs setup, he is using it to drive another amplifier. The difference between this and a typical discrete setup is that his amplifier *also* has a volume control on it. Ideally, the amplifier input would go straight to the input stage without passing through a pot.

Yes, the stages are connected slightly differently in discrete versus integrated (the latter doesn't need cables) but that hardly constitutes a big difference.

BTW unless an amp is using some proprietary room-temp superconductor, it will not have ZERO noise (hiss/static, not hum/buzz). Johnson Noise is an ugly but rather inevitable reality.
post #9 of 11
Quote:
Originally Posted by poo View Post
I have done the same comparison with my iPod nano, and Classic and found the difference surprisingly significant; specifically the additional noise. Line out produced far less noise in my experience (especially noticeable through IEMs in my case). In fact for me, the difference in extra noise alone via headphone out was convincing enough to keep my Pico and always use line out of my iPods.
I just tested this. With my 5g iPod the headphone-out registers -80.3557db for noise and the Line-Out registers -80.4447 a difference of -0.0890db. Your headphone outs must be very different from mine. How did you do the level matching for your tests ?
post #10 of 11
In simple terms what the OP is doing isn't "wrong". However, you are taking the amplified signal out of a headphone jack, amplifying it again and then again.

Everything has distortion and at each stage you are amplifying distortion and adding distortion. What the effect of this on the sound is dependent on your system and your hearing.

When people use a tube amp as a preamp they are deliberately adding a type of distortion to get a type of sound coloration that they like.

On the ipod issue: I have listened to my ipod from the headphone out through an amp. When the signal is fed into a decent headphone amp like in my case the Darkvoice 332, the distortion is quite audible and using the LOD is an easily noticeable improvement. On the other hand I am forced to listen to the Sansa Fuze through the headphone jack and the distortion is not as annoying (but it is distorted).
post #11 of 11
Thread Starter 
^ does an amp have distortion at every volume level?

because by trial and error..i set a %75 volume level in boa..where there was inaudible distortion...and maximum drive.

if i set Boa at low level and Edge at high level then the Sound is flat...no drive.
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