If you are a power user of Yamaha and Steinberg you've gotten used to the integration of your Yamaha hardware Synth and your Steinberg Cubase software via the Editor VST. However, the initial release of Cubase Series 8 seems to have broken the function (Ed.: fixed with version 8.0.10 3/12/2015 and later) - you can still take advantage of the features and benefits provided by the VSTi routing using this advanced External Instrument setup. 

Here is a tutorial on creating a custom CP4 piano Performance using the S6 piano (APIANO3) for the Main Voice and the CFIIIS piano (APIANO2) for the Split Voice and saving it to a Performance location for instant recall.