Hey there
@Cuzzie . We have used all sorts of different stuff to make kava, from green teas, black teas, herbal teas, nut milks, chocolates, fruit juices, sugars, honeys, simple syrups and all manners of combinations of the aforementioned While I have heard many times that people really don't enjoy a bit of caffeine with kava, I find that this really only pertains to mixing something like coffee and kava, which has quite a bit more caffeine than say something like a strained Sencha. Rooibos works quite well with kava, and highly suggest that or Honey Bush for home brewing.
If you ever want to try the stuff we are mixing up these days, check out Karunakava.com and use code DRINKKAVA for free shipping on orders of 50$ or use code rooted for a discount on any order.
I hope this helps, happy explorations.
Bula Vinaka