I agree with rumbleseat, the Naiant PFA is a good way to go. I really don't like using a battery box in the chain personally, the PFA isn't that big, is built really well, and one doesn't need to worry about battery condition. Another thing that is nice is the connections can be easily taped which is harder/messier to do with a battery box or preamp with 3.5mm connections in my opinion, if cable separation is ever a concern of yours.