Shielding speaker cables don't benefit much as the termination itself is a very low impedance device ( speakers). Shielded cables work better for interconnects as input impedance are typically around 100kohms.
For power cables the transformer primary itself will be in 5 to 6 Henries range. So ño RF/ EMI noise can get through that. But due to core saturation any eddy current involved it can be a source for EMI radiation. I have noticed just potting the transformer with a tin and grounding the tin enclosure reduced EMI noise in my phono preamp.
For power cables the transformer primary itself will be in 5 to 6 Henries range. So ño RF/ EMI noise can get through that. But due to core saturation any eddy current involved it can be a source for EMI radiation. I have noticed just potting the transformer with a tin and grounding the tin enclosure reduced EMI noise in my phono preamp.