Audioquest William Tell vs Obsidian

I am looking on opinions for my speaker cable upgrade path. I presently have an 8ft. pair of Audioquest Pikes Peak biwire in my system. Basic system is: ARC Ref 75SE, Vandersteen Quatro CT Wood, ARC LS27, ARC PH8, VPI Aries 3 all mods with Lyra Delos, Aurender A10. Audioquest Water & Niagara interconnects.

I demoed a set of Audioquest William Tell: Bass wire & zero for true biwire configuration. These are a huge jump in performance in my system and I am ready to buy them. However, I noticed that Music Direct has a set of Audioquest Obsidian 8ft. biwire speaker cables for a huge discount and this would be just about the cost of a new William Tell setup. 

Anyone have experience with the Obsidian or any advise?

No experience with Obsidian, but, I too, auditioned the William Tell's and agree with you. In fact, I bought a set for both of my systems.
The new cables by Garth are amazing, and are worth the money-though I some might be put off by the price.
I think Obsidians were an older model. I can't find them on the website.
Vandersteen now has a forum on his website.
Please join us and ask your questions there.