Unless the SPDIF cable is much longer than 1 metre it is doubtful there will be an advantage that is unless there is a ground-loop in the system, as the iDSD micro SPDIF input is not isolated (as it is mainly intended for portable/desktop use).
In this case, the galvanic isolation offered by the SPDIF iPurifier would provide improvements.
It should be noted that the spacing of connections on the iDSD micro does not allow the SPDIF iPurifier to be plugged in directly while having the line outs in use, so an adapter cable would have to be added.
