Simple line mixer for Loudbox

[el guitana]

I just picked up a used (cheap!) Fishman Loudbox. I owned a new one for a few days last year, but returned it for a PA system. Have missed it a lot, and have recommended it to others for good powerful acoustic sound. These have awesome sound, are simple and powerful, but only have one input.

Anyone know of an inexpensive line mixer so I can blend a couple instruments and voices?