Only good for Electromagnetic Interference (moving current through a wire, induces an electromagnetic field, Physics 101). These beads suppress the interference and the resultant noise E.g the EMF (electromagnetic field) generated by battery power cables may induce a noise in the RCA cables which will be amplified by the amplifier. With the triple and quadruple shielding of modern RCA cables etc. these beads are fast becoming a thing of past and generally not needed anymore. Today if there is a noise or whine in your system then snapping these filters onto the signal cables will not likely prove to be helpful because of the aforementioned shieldings, in that case you would be better off by moving the cables away from the source of interference. But still if you have them lying around, just snap them on, wouldn't hurt or affect the sound in anyway.