Circling back to let everyone know what I’ve done. First, thanks for the suggestions. After doing a lot of internet research, I hit upon this review: https://positive-feedback.com/audio-discourse/ice-age-audio/
I emailed Rick Parker at Ice Age Audio, and after some discussion I ordered the Frankencable power cord and the OFC speaker cable, jumpers and interconnects. (I also ordered two more power cables and an HDMI cable). Altogether I spent less than the suggested speaker cables and interconnects would have cost.
I had also corresponded with Christopher Jendralski at The Cable Company. They have a lending library of cables, but his suggested speaker cables and interconnects would have cost 3-4x what I ultimately spent.
Today I connected all the new cords and cables (along with an upgraded electrical outlet), and all I can say is
Oh. My. God.
I’m hearing things I’ve never heard before. The sound stage is both broad and deep, and the detail and clarity is mind blowing. I’m hearing things in familiar music that I’ve never heard before. Favorite songs that I’ve listened to for years are like they’re being heard for the first time. I intended to just listen to a few songs to see if I heard any difference, and wound up listening to song after song for hours. The sound is just a little on the bright side, but I was told to expect that until everything is broken in.
Are there better cables and cords available? Probably, but at this price I can’t imagine a better value. Having upgraded the entire loom at the same time, I can’t say which component makes the biggest improvement, overall, the difference is, to my ears, simply outstanding.