> If noise gets into the pre-amplified signal Nah-- it's about high frequency noise getting in via the speaker lead, and coupling to the negative feedback of t

> If noise gets into the pre-amplified signal Nah-- it's about high frequency noise getting in via the speaker lead, and coupling to the negative feedback of the amplifier stage, and getting rectified and amplified. Yes, most interference is via line level inputs, but it can easily be via the "output" as well.