The process of amplifying the audio signal is inevitably accompanied by its movement through the conductors. This can be both tracks on the PCB, and cables that connect the equipment. It is known that for the passage of the signal, at least 2 wires are needed. One of them is called the general, the second is the signal one. In the ideal case, the resistance of these conductors is zero, and parasitic parameters (capacitance and inductance) are absent. In real conductors, for example, signal audio cables, there are parasitic parameters that affect the passage of the signal through these conductors. These can be wires between the signal source and the amplifier or between the amplifier and the speaker system.
Measurements of audio cables I started with a simple Chinese "lace". As a result of the measurements, it turned out that the characteristics of its two signal wires relative to the common wire differ markedly. Predictable were poor characteristics at high frequencies.