Most transparent open & dynamic cables out there?

I would look for a different solution. You're asking the cables to do too much here.

I agree with Zd 100%.

Your speakers provide three different sets of adjustments for fine tuning their high frequency response. Have you tried all possible combinations of settings?

I would expect that those adjustment provisions would have much greater impact on high frequency rolloff and perceived speed than a change between any reasonably designed cables would provide. If they don't solve the problem, or at least come close to solving it, something other than cables needs to be addressed.

Regards,
-- Al

+2 Zd542.

change the amps...

For the ones I have heard: Gabriel Gold Rapture R or Stealth Hybrid. You would require 2 sets of each for biwire. You might consider Antipodes Kamako....a little faster and ok for Classe....I find classe a little thin, dark and slow. I am using MG Audio Planus III and am really impressed but they aren't suited for biwiring.....you could call Greg there just to check, they are great to work with.
That said, you might want to see what Steve at Gabriel has in stock.....I have a nine foot pair of Rapture R you might talk me out of.