I've tried this. It is not that I am disinterested. Perhaps a top tier selection of light bodied coffees brewed to amber strength with a coffee to decaf coffee bean ratio of 30:70, would be fine with kava,traditionally prepared, instant, or fresh green. Perhaps. Coffee is quite dark and takes up a lot of resources in my body, especially working the digestive system, kidneys, ocular muscles and brain capillaries, sinuses, and adrenal glans.
I can confidently say I very infrequently add sweetner, even natural--such as honey--,to kava. Milk, occasionally, as well as almond milk or coconut water. These lipid rich milks are great for brewing coffee as well. Perhaps a carefully created lattee of coffee bean and kava root would please lovers of both.
Flavor wise, I find they overpower eachother competitively. In my body, I think they continue to fight for territory. Coffee and kava together dry me out at and I find the positive effects or sought out qualities of each plant are muted. For me. I can sometimes have a half cup of coffee, or a lightly brewed black tea with or after kava. The only source of caffeine that I seem to be able to smoothly integrate during a kava ceremony of my own is a nice cup of green tea.
Nonetheless, I treat myself to kava a couple mornings a week and one or two mornings I have coffee, so I am passionate about both. I also enjoy exploring blends of other herbs into eachother. Although my post does not support the discussion, I am glad to share my trials and experience with this and I hope your creativity will allow you to find a recipe that allows me to try kava and coffee prepared together and say, "yum". Good luck,
bula!
