Yes i know this, is why i asked, and i thank all for their thoughts so far. I'm not trying to muck people around, but today has been very busy for me. So I apologize for not being able to fully explain myself earlier. Now that i have time, i shall explain further, but, this is going into the snake oil / audio cables are all the same territory.. I have been made aware by others, that by putting a 0.47uF np cap across the mains in a house, it will 'alter' the sound of a hi fi system. I have tried it and verified that this really is the case. My reason for this post was to try and understand how the f... putting a cap across the mains could have an effect to such a degree that multiple people can verify it easily. my thoughts are that capacitors react to ac waveforms at different frequencies (dependent on value). But how does that manage to affect any audio equipment which in itself will normally have either a switch mode or linear power supply, that also has its own filtering system comprising of capacitors, diodes, and regulators as a minimum. Not forgetting that there are then all the audio circuits after the supply stage as well. I'm theorizing that by acting as a line filter to some degree, that it allows the equipments power supply to act more efficiently for its own internal needs, rather than having to combat external mains borne noise. So, there you have it. an item that does result in a change to reproduced audio. I personally would like to know if my suppositions are correct or not.