John, in principle any balanced input can be driven directly from an unbalanced source, provided that the voltages and impedances are otherwise compatible. Often a simple adapter will suffice for this.
If you're going to convert an unbalanced signal source to balanced operation, however, the optimal place to do that is at the source--not at the input of the balanced device. You'll get none of the noise immunity that a balanced input offers unless the line itself (connecting the source to the balanced input) is balanced.
However, if you're sure that this noise immunity isn't needed in your application, then what Harry at Beachtek says is right.
--best regards