Power conditioners are very dependent on your location not just on your system. In the UK we generally have good clean power and I live 4 houses away from a small electrical sub-station. Probably for this reason power conditioners make no improvement, and actually make the sound worse. In the US I believe that the quality of the power is poorer and many seem to get big improvements from conditioners. But it will still depend - rural locations vs city apartment blocks will have very different quality of electrical power.
Re power cables - there are too many brands to know more than a handful but of the ones I have heard I can recommend Shunyata. The mid-series Alpha range by them are particularly good value.
Re power cables - there are too many brands to know more than a handful but of the ones I have heard I can recommend Shunyata. The mid-series Alpha range by them are particularly good value.