unless you find a switch for the +4 to -10 conversion on the efx unit.
If you running balanced +4 into an unbalanced -10 FX unit your likely to overdrive the input unless there is an attenuator on the input. Ive got lots of +4 unbalanced lines and forgot and recently fried an FX unit. Doh!
4 possible answers hanging on the words "it depends"
SoMm