I use MidiOx and MidiYoke with no trouble on a P233. I use it to run both XGworks and Cakewalk at the same time. I connect the keyboard (PSR740) to XGworks for the XG Editor and use Cakewalk for the StudioWare. Yhe output of both are set to MidiYoke Junction 1 as is the input of MidiOx. The output of MidiOx is connected to the keyboard. Hubi's loopback works just as well but I like the extra features of MidiOx.

Bryan