They don't matter so much that people should spend big bucks on it.
However, it's an inadequate approach to consider the relevance of power cables in terms of the "last two meters". In many cases, the earthing wire of such cables form an unwanted but direct ground path in between audio components (if both components have three wires power cables). Depending on the earthing/grounding scheme of the components, significant signal ground current might circulate through that path and be afffected by noise riding along the power wires.
Some power cables might in some cases mitigate the effects of such more or less obvious ground loops and account for some audible differences. However, it would be a very inefficient way to proceed; there are much better and cheaper options to fix such problems.
Which is why all my power cables are cheap, ordinary ones, if possible hardwired.