I am not an electrical engineer and I do not pretend to be one nor do I play one on TV.....
But....did you stay at a Holiday Inn last night? Because apparently, that may qualify you as an EE. LOL!!
I also have a preamp with a separate power supply, and have considered the same path. I own a Cary SLP-98P F1, and I know of one company that makes an upgraded umbilical cord for the Cary. Revelation Audio Labs (RAL). I even know one guy who owns the RAL and swears by it, I have also seen a couple of SLP-98's list on Audiogon with the upgraded RAL cord.
I also have heard a rumor that Cardas also supplies and upgraded umbilical cord for the Cary, but I did not check with Cardas to verify this.
I did go so far as to buy a used RAL umbilical cord, that was used on a Supratek and according to RAL was also compatible with the Cary, but it did not fit, so I sent it back. At this point I'm just listening to the preamp with the stock umbilical, but upgraded tubes and power cord to the power supply. I have never actually heard an 'upgraded' umbilical cord.