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Will "double amping" damage equipment?

Discussion in 'Sound Science' started by baskingshark, Aug 20, 2019.
  1. baskingshark
    Hi sorry I'm quite bad with sound science, but just to check, will double amping fry any equipment?

    I'm thinking of this setup:
    PC (line out) to Tempotec Sonata HD (which is a DAC/AMP combination) to Fiio A3 (AMP) to IEM/headphones

    I tried it with PC at max volume (sonata HD has no volume controller), and just controlled the volume at the 2nd amp (Fiio A3), and found that the sound is a bit fuller for soundstage and details.

    I know there may be amplified noise/distortion that may adversely affect sound quality, but will this cause any damage to the 2nd amp?

    Thanks for your advise and input, greatly appreciated.
    Last edited: Aug 20, 2019
  2. bigshot
    Why would you do that? Is the DAC's amp not the proper impedance for your IEMs? A DAC/amp without a volume control? Line out to amp to amp? You aren't using the DAC as a DAC? I'm not understanding the concept here.
    Last edited: Aug 20, 2019
  3. buonassi
    I too am curious if it can harm some amps if being driven by a source with low output impedance (lower compared to line level standards that is). I know that amps can clip if input voltage is too high. But remain curious about impedance.

    Good to know these things. Though like you @bigshot I don't see a use case for it.
  4. castleofargh Contributor
    the fiio A3 gives:
    Input Sensitivity 2.4 V (GAIN=L)
    0.8 V (GAIN=H)

    the Sonata doesn't give much in term of relevant data, but assuming that the voltage will remain somewhere in the area it is at 32ohm, when all is maxed out we would get something hopefully around 1.9V.
    so with all those assumptions(and I actually do not have a clue, only educated guess), if you use the Fiio on low gain, you're probably fine with the Sonata/PC maxed out.

    there is no reason why anything would get damaged unless you massively clip the second amp for a long time by feeding it way too much voltage. in this specific case that doesn't seem to be a problem, and in any case if you were to send way too much voltage, you would not find the sound enjoyable at all, as it wouldn't sound much like music anymore ^_^.
    so as far as I can tell, if you like it that way, use it that way.
    baskingshark likes this.
  5. castleofargh Contributor
    I can't think of a reason why that would cause damage. I won't claim that there couldn't exist a case somehow somewhere, but at least it's not going to be a typical situation. I'd expect the second amp to pretty much give zero F, to use the technical lingo ^_^. for the first amp on the other hand, I still can't think of a cause for damages, that's probably not a thing. but there may be amp designs where being used pretty much unloaded(the second amp's input being anywhere between say 4k and 10kohm), might result in sub par measurements. but even that I wouldn't count as typical, just that it may happen.
    without knowing anything about anything and having to guess anyway(not cool, guys), I would on the contrary expect that many first amps could measure their best or near their best when unloaded(plugged into really high loads).
    for more, like something I could actually say with confidence:sweat_smile:, we'd need a specific example and a serious amount of information about the amps, or even better the ability to measure the gear while used that way and driving a specific headphone at a specific level.
    buonassi and baskingshark like this.
  6. baskingshark
    Thanks @castleofargh for the detailed advise. Quite useful info for sure.

    @buonassi and @bigshot the reason for me using the fiio A3 (2nd amp) is twofold:
    1) the Sonata HD has no volume controller but the fiio A3 has
    2) it seems the Sonata HD gives popping and clicking noises everytime i fast forward or skip songs on PC (tried on three PCs), not sure why. This disappears when the fiio A3 is added. The sonata HD when used with phone has no clicking.

    Yeah but taking into account the valuable feedback from you guys, i think I'll just find another DAC that has no amp component.

    Thanks again!
    Last edited: Aug 20, 2019
  7. Scgorg
    Remember that there is no real difference between a 2V line level signal and a 2V signal attenuated from a max output that is higher assuming the signals are equally clean. If you have a line out with -120dB THD+Noise then there is no difference from an amplifiers output that is -120dB THD+Noise. You could in theory use a speaker amp to feed line level signals if the signal is attenuated enough. The line out is just 2V at lower THD+Noise than what most amps can muster. 2V is 2V, doesn't really matter where it comes from as long as it is carrying a signal.
    baskingshark likes this.
  8. buonassi
    so amperage, and impedance matters not for line level inputs - it's purely a voltage game?

    And from what I gather, the higher impedance from typical line level outputs (IE 10k ohms) is there to reject noise along the circuit? Why is 10k ohms the standard and how would that improve SNR vs a 1ohm amped line out?
  9. Scgorg
    Line out is typically just a simple voltage output. The amperage depends purely on the impedance of the input/output in accordance with Ohms law. I'm also pretty sure most line outs aren't that high in impedance, typically you want a good ratio between output and input, often in the realm of double or triple digit impedances on the output and 5 digit values on the input. Modern devices has typically pushed the output impedance of the line out down as to secure the best possible ratio between output and input.

    I think your 10KOhm figure is from line level inputs rather than outputs, I have never seen a product with such a huge output impedance.

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