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?