This feature is only available in the full version of Halion Sonic. In the amplifier subpage of the edit page on every drum layer you can define a different output for each note. Together with lots of other functions these are not available in the free halion sonic SE that comes standard with cubase.
It makes sense to try out the 30 day demo of the full halion sonic to see if the vast amount of functionality’s suits your needs, but i admit this could have been a very nice feature if it was opened for the SE version too.
The full Halion Sonic is quite a beast though but there are others in that segment of the market too.
If it’s about multichanneling drums i would indeed rather point towards the new groove agent 2 that is specifically made for drums and actually has plenty of very decent kits and far more functionality than you will find in the halion sonic which is an overall workstation. Also the content available to GA2 is only limited to your imagination since the database is open for importing own samples.
kind regards,
R.