Who else is using old cables/interconnects, and is happy?

@justmetoo Lol Michelle your pitiful Mark Levinson/Burmester system is so "not sufficient high end" indeed! :-p

Happy here....
I have a few in rotation but as discussed below by @noromance, I generally go back to solid core.  Harmonic Technology did it well with multiple, individually insulated (with foamed PE), OCC, solid core wires of different sizes.  I also sometimes use heavy gauge NOS Western Electric KS-13385 wire, as well as some newer Duelund DCA12GA wire doubled, twisted, and bi-wired for a total of 6 awg to each speaker per pole.  Fortunately, due to using monoblocks, my run is also short - typically 1M.

Many years ago I read an article written by McIntosh which stated you could use a lamp cord for speaker wire and not notice any real audible difference.  I have used cheap wire, medium priced speaker wire, and tested expensive speaker wire.  The look of better wire is appealing, but I couldn’t notice any real sound difference.  Speakers were Wilson and Paradigm.  Now I am using wire that cost 150.00 for two 10 ft runs.  Sounds great.  Will never spend any more on wire.

A representative inside of McIntosh factory once told me that the engineers there maintained that there was no noticeable difference in various interconnects and speaker wire. At the time I had the Mac 1000t pre and 2102 amp.
 An audio reviewer who was a personal friend demonstrated otherwise in his system. That's when I first started to think that McIntosh was not transparent enough in its presentation to reveal differences. After trying other manufacturers products, I came to realize that the  comforting smooth sound of McIntosh came from a scrim over the presentation that obscures much micro detail. Well, I sold the Mac system and from that day forward have heard the difference in virtually all of the ICs I have owned since.

I'm skeptical though that cables matter much

Well @tk21, with so many cable companies selling direct these days with generous trial periods it’s certainly not too hard to find out if you’re right, so why not try?  You might be surprised.