This question appeared several times here on the forum and here`s my solution:

In Acid, Cubase or other programs that support this feature:
Go to preferences and find the entry that says something like: "Close Audio and Midi drivers if Acid (or the relevant program) is not the active application", and check it.
In Acid 7 its the 8th entry in the first tab. In cubase go to "Devices"/"Configure Devices", VST Audio System, check "Deactivate Asio drivers when program runs in background".

(Sorry my apps run in German language, so this is my personal english translation of the menues ;-))

This adjustments closes the audio (and Midi) drivers whenever the application is minimized and therefor not the active application. Then the driver is free for another application to use it.

HTH, Sandra

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