Good to see you going the interconnect route. I have found my CD -> Pre cable to be vital to the sound in my system. I have a Kimber Power cord on my tube pre and it cleaned up the background. As your system improves you will notice changes more because the sytem as a whole has more resolution. This is why the subject is so debated. A bad system may have no effect at all. A reference system may have dramatic effects.
One thing that would be free to try is if you have improved the speaker cables go back to your $40 monster interconnects. You may notice more of a difference with the better speaker cables in place. The power cord is a good idea as well. I have been wanting to try the Signal Cable PC too, so it will be interesting to see what you say. A power cord can work wonders on cheap gear with poor power supplies. On expensive gear it may do nothing because it has super power supplies and regulation built-in. Don't be afraid to experiment.
One thing that would be free to try is if you have improved the speaker cables go back to your $40 monster interconnects. You may notice more of a difference with the better speaker cables in place. The power cord is a good idea as well. I have been wanting to try the Signal Cable PC too, so it will be interesting to see what you say. A power cord can work wonders on cheap gear with poor power supplies. On expensive gear it may do nothing because it has super power supplies and regulation built-in. Don't be afraid to experiment.