Check out this article:
http://www.harmonictech.com/news/docs/harmonicreferenceACcord.pdf
While I am not specifically recommending this power cord (although I have enjoyed Harmonic Technology products in my system over the years), the point of the article is that a good cord going into your power conditioner can make a very big difference.
Of course, bear in mind that there is a whole crowd on this site who thinks that all power conditioners are harmful...
http://www.harmonictech.com/news/docs/harmonicreferenceACcord.pdf
While I am not specifically recommending this power cord (although I have enjoyed Harmonic Technology products in my system over the years), the point of the article is that a good cord going into your power conditioner can make a very big difference.
Of course, bear in mind that there is a whole crowd on this site who thinks that all power conditioners are harmful...