I was wondering about how double amping works. I think I understand how things work in relation to distortion; that the second amp will end up amping the first one's distortion etc. So if I were to guess, I'd say that if an amp had audible crosstalk and you doubled amped, you'd make the crosstalk even more audible. Is that right?
Also, how does this work in terms of output/input impedance? Is that something that factors into amplification or does a very high input impedance prevent these things from playing a part?
Also, I was looking into understanding DACs some more, and what I read is that when a DAC has an output stage, it will always amplify the signal to line level. What is meant by 'line level'; what is its significance?
there are many factors to account for. in principle it's nothing much, one signal get in the first amp, gets out with a gain(voltage gain on most audio amps) and into the second to get out with another gain. in some situations, you can get good results by using several op amps instead of trying to get a huge gain from just one. it really depends on a lot of specs and what we're trying to do.
but to get low SNR from the first amp it would be better to push it close to max volume. while max volume might get more distortion(and maybe some clipping). so there is that decide.
whatever gets out will indeed be amplified by the second amp. so better have a good margin between sound and noise/disto.
then there is the problem of the first amp reading a load of a few thousand ohm, so how it deals with that depends on the amp itself. but it should be ok.
then there is the problem of the second amp not clipping from too much voltage going in. that can very much not be ok.
I guess all could be determined and with the right amps and right settings it could work ok, but it can also go bad very easily.
about crosstalk, nope, if all the second amp is doing is amplify left and right, the original left signal and the right mixed into it by the first amp will just both have more gain. so it won't be more audible, both will be louder but separated by the same margin. but of course if the second amp also has a terrible crosstalk it's another matter. but still if I think about it, let's say at some point the signal from one side goes to the other 60db quieter in one amp. then if you do that twice, the last mix up will in fact take the -60db signal from the wrong side to bounce it back with the rest where it should be with another -60db attenuation. so I don't think that matters much as long as both amps have an ok crosstalk (I may be totally wrong here about crosstalk, that's just my own simple logic and it may not be accurate).
still by principle I'm not a huge fan of double amping.
