Power conditioners make no difference at all to the sound, with one exception: If they are true isolation transformers - which most of them are not, because it's expensive to build one - they can cure ground loops and other rare ground noise problems.
Always remember: You do not listen to your mains power, you listen to signals generated from flattened, filtered DC.
Again: You don't listen to your PSU. Apart from rare cases of different handling of ground loops and interference issues with multiple cheap SMPS without sufficient output filtering on a single outlet/circuit, there will be no audible difference between equally powerful PSUs.
Power cords don't matter at all. The cabling in your walls is regular unshielded stuff from an industrial supplier. So are the kilometers of cables outside of your house in the ground and the dozens or even hundreds of kilometers of power lines from your town to the power plant. Just think about this for one second, it should be pretty obvious how the last 2 m from the outlet to your HiFi device absolutely do not matter anymore.