“But what really surprised me were the speaker modules – I never knew there was so much noise in the amplifier/speaker chain.” Nick, Surrey
Vibration is the problem
By design speakers vibrate air particles to produce sound – 50% of the energy into the room but 50% goes into the cabinet as the cones move back and forward.
Some energy is absorbed by the cabinet but a lot escapes through the speaker cables into the amplifier, metal being an excellent mechanical conductor. As the whole system connects to the amplifier unwanted energy travels into every component and every circuit, creating “microphony”, spurious signals.
Read more here (and scroll down) how the Quiescent speaker modules are excellent absorbers for removing damaging energy. And there are mains modules …