Lot of solutions out there. I was looking for an automotive solution I ran across, but now I can not find.
You can look for Line Balancing transformers (Jensen is very good) or unbalanced to balanced line drivers. It is like the Turbo1 you have but with the addition of balanced outputs.
Some Balancing transformers are passive and do not add gain and do not need power.
You could use two of these:
http://www.rdlnet.com/product.php?page=164
I'll post here if I run across the automotive solution I was talking about. Look at all the usual car audio suppliers like Crutchfield etc.