Pair of 2s lipos in series is best for the emaxx (old or new emaxx?)
Whatever brand you go for, just avooid maxamps or ebay 'no name' lipos- have a read of this little doozy:
Emaxx FAQ
I have one question though- when you said you ran 6s lipo on your mambamax & it blew up, did you have a an actual mambamax esc (and not an MMM/MambaMonster), as in, the one thats rated for 3s lipo, or 4s with some mods?... would explain the fire and flaming death it suffered....