The quality of the powercord will determ the purity and the momental capasity of the current led into the powersupply. Add ing more momental capasity will give a stronger bottom by increasing dynamics. That won`t in any way decrease top-end quality. By increasing the powersupplys dynamic capasity high freq distortion will be redused as well. To a not to skilled ear that my sound like a redused top, but fact is that it`s just cleaner.
It`s all about how much current that`s added to the powersupply and the quality;how clean that current is. Stranded cables creates a lot of internal cross-over distortion when current flyes confused between the many tiny conductors. This also dramaticly reduses dynamic capasity as well. Hairthin conductors in it self have wery poor capasity and steals a lot of dynamic power.
Btw; I`m using DIY massive (and shielded) PC`s, nothing comes close to massive, thick massive :)