Power cables for HiFi systems are very important as they must mainly carry power to the amplification units trying to avoid any type of interference during the journey from the isolation transformer (or directly from the home network, which we do not recommend as described in the Transformers section insulation for HiFi .
There is no need to spend thousands of euros on power cables, as unfortunately the market for these components is a bit malignant, just buy a well-shielded cable. There are many cheap cables on the market that are perfect for this task.
Another important aspect relating to power cables is their position inside the HiFi system and the sources of disturbance that may be nearby, so it is good to be as tidy as possible, without grouping too many sources, such as TV, PC, decoders, which can still disturb.
Clearly these measures can make the difference using high efficiency and sensitivity speakers above 100dbe with high power amplifiers.