[GerardJ]

Thanks for your comments!
My experiences regarding biwiring is somewhat different from yours. Biwired cables are often just single end cables with a split at one end, not different from single ended with a jumper of the same quality as the single end cable.
This is also in agreement with the answer I got from Ivan regarding my question: “What is better: biwire cable or single ended with jumper?” Ivan’s answer: “... it really comes down to personal preference.” So not really SQ issue!
It is quite a different ball game when using 2 sets of speaker cables. That is also what Ivan tried and posted about post on 12-24-2016: “TAD R1's get Dual runs of WW Silver Eclipse 7 speaker cables” . He reported: “My initial listening impressions are quite favorable. I like what I'm hearing, more dynamics and detail. Both Rich & Mitch also concur, this was a worthwhile upgrade.”
This is also my experience when I did an experiment using my old MIT M-770 cable for Low in combination with my WW Silver Eclipse 7 for High on my TAD-E1. Even with this somewhat uneven combination the increase in detail and dynamics was impressive and with also a much larger soundstage!
So I am very curious what 2 sets of WW can bring and also if combination with version 8 could be used.