well you realize this is a LONG shot lol
Get a set of headphones, and cut the headhones off so you are left with the head and cable, seerate the cables, attach one side to the + on one speaker, and the other side to the + on the other speaker (left and right) get another piece o cable (more spare headphones lol??) and atttach them to the - terminals and then attach the other ends to the case! (so they are grounded - 0V)
Im not sure if that willl work in theory, and it probably wont in practice! the amount of resistance in the join in the cables would be huge! and spoil it. i dont know if you get converters for them! you might just spoil two perfectly good sets of headphones lol!
anyone else know? no doubt someone will say what iv just said is completely wrong... so id hold off taking the knife to the headphones the now!