i don't believe you can just switch batteries to a different voltage...
v=i*r so if you go with 2*v then you need to change something, and you can't change the resistance so you'd somehow have to limit it to half the current to stay within the parameters of how they set it up (or so i'd think)... but i'd double-check with your local audioquest dealer or try calling them yourself (i actually work at a shop that sells a lot of audioquest, if a customer came in asking this, worst case i could try and call them and see if this is a 'supported' or technically feasable change).
v=i*r so if you go with 2*v then you need to change something, and you can't change the resistance so you'd somehow have to limit it to half the current to stay within the parameters of how they set it up (or so i'd think)... but i'd double-check with your local audioquest dealer or try calling them yourself (i actually work at a shop that sells a lot of audioquest, if a customer came in asking this, worst case i could try and call them and see if this is a 'supported' or technically feasable change).