Lloyd,
In reproducing high performance audio the part of the cables must be the lesser; in fact if absent is better.
We do not need sonic singature from cables but deliver undistorted signal (as much as possible).
Already you are having a "nice" sonic signature from your tube dac and tube preamp (I have tested the same pre as yours and is a good much with Antileon; but Antileon needs balanced preamp to deliver the most...I ended up either with dCS direct or with the latest Viva Audio Linea XP which is one of the most musical preamps ever heard; and still audiophile too), you're having musical and sweet speakers, so IMHO you don't need more "sauce" from the cables.
If your dealer can help you try the Stealth Dreams or Jorma Prime.
I think -with Dreams- you should see the power of Antileon and have bigger dynamics, more depth and broader soundstage, clarity as well and absolutely no harshness or edgy sound.
More neutral in the good way and faster (or equally fast with Nordost).
Previously used, Nordost valhallas, Stealth M5000 (sweeter sound), Siltech g5, g6 (Siltech is internal wiring in Gryphon), Virtual dynamics, Acoustic zen, Gryphon (entry level, same as Siltech) among others.
In general I believe that every cable (especially power cords) should be tested in your system first.
And only after that; decide.
The same applies with Speaker cables, I had Yter which is internal wiring of Strads and Annis, then Valhalla (lacked the depth of Yter and sweetnes also; but more tranparent and fast) and then came Stealth Dreams just better in every way and all the virtues of the previous.
But all is system dependant...so try before you make any change. All IMHO.
George.
