which component should i put the better cable on?

Thanks for the quick responses already! Ultimately i will try them on both but more opinions would be welcome! More detail: The amp is a Outlaw 750 with the upgrade to a male socket because the amp was hard wired. The pre amp is a Outlay 950. The expensive power cord is a Electroglide Reference gold 2000, brocken in. The other cord is a silver cord with Wattgate 350 audio grade one one end and a hubble hospital grade at the other end, if this info helps any! I would really appreciate all and any opinions on where the cords are better off on! Also personally with my system i find the Outlaw amp a little on the bright side so if one of these cables would help reduse it please let me know! Thanks so much!
Phil

Thanks again especially to Bob Bundus for the in depth explanation of synergy! I did some experimenting and i found that the better power cord sounds best on the pre amp, however i wish i had another Electroglide reference 2000 gold or better for the amp because i have to say i noticed a huge difference with the electroglide poercord!!! I believe i believe!!! It is amazing what a really good quality power cord can do for your system!!!! Thanks to all!!!
Phil