In your experience, do mains leads really make a difference, and are the expensive ones really capable of offering value?
Mains cables do change the sound of audio equipment. Unfortunately there’s a lot claims made about mains cables that are exaggerated. I suggest that the effect of a mains cable is not as important as interconnect, but is still significant. Value for money judgements are really down to the system, where these relatively small improvements make the difference between a good listening experience and an exceptional experience.
What I do NOT condone is high pricing for cheaply manufactured cables. If a cable must use expensive materials to realise truly high performance, then so be it. But the use of expensive materials for bullshit (leads to high prices) but not for sonic improvements is not the way forward. It just upsets customers. I believe the reason why the performance of audio equipment is altered by mains cables, may be due to the influence of RFI on the mains. Generally I’ve found in the development of mains cables that dielectrics with improved high frequency performance possess better sound quality compared to normal PVC insulated cables.