EMI may well cause secondary and unwanted effects in amplifiers. One source is the speaker cables that are not only information bearers for analog audio signals. They are also RF antennas. The problem is that amplifiers may not have sufficient RF attenuation for RF related EMI fed into the amplifier via the speaker cables. As most amplifiers have an internal feedback signal from speaker output, RF noise can be injected into the negative feedback loop of the amplifier. This may well cause secondary effects for example within the micro-dynamics.
