howdy folks,
i found the fix for the error myself:
when you klick on "speaker test"
it says you have to go to
windows cotrol panel> multimedia > audio > advanced properties
and set "rate conversion quality" to "best"
after i have done this
by klicking
Settings > ASIO Control Panel (the menu of the kx manager)
finally the ASIO control Panel DOES appear,
and in CubSX I don't get the error anymore
AND I have 5msec latency now >> *keeewl*

)
Greets
funkyP