Hey Mr M,
Have you confirmed that Windows is reading your EMU as your default device for common applications? (Found in the Audio section of your control panel).
If you are talking about this happening while Cubase is running, be sure that the "Release Driver when Application is in Background" is checked in Device Setup.
I know you are very experienced, so I fear it must be more complicated than this...
Asus R500A-RS52, Windows 8, 2.6gHz i5 -3230M, 6GB RAM,
Cubase Artist 7.0.6, Wavelab Elements 7, Focusrite Scarlett 8i6, The Grand 3, Melodyne Essential, Superior Drummer, EZDrummer and Pop! EZX, Samson CO1, Yamaha P-35, Mackie MR5mk2 monitors, and more....My tunes on: Soundcloud