I have a Mbox 3 Pro and it’s impossible to change the buffer size when Cubase is running. The Mbox panel says: “The buffer size control is disabled because an application is streaming audio.”
The option “Release Driver when Application is in Background” is checked in my Cubase setup, but it looks like Cubase doesn’t fully release the driver when he is in background.
The only workaround I found is to turn on my Mbox after loading Cubase. Then I have to select the Mbox driver (ASIO 64-bit) in the Device Setup panel and set the VST connections manually. By doing this, Cubase releases fully the audio driver when it is in background and the Mbox panel allows to change the buffer size. BUT, the major problem of this workaround is that I can’t use any MIDI on the Mbox when I turn it on after loading Cubase.
Please note that this problem was also in Cubase 6.5. I was hopping that Cubase 7 would not have it… I don’t have this problem with other DAWs.
Here my setup:
Audio card: Mbox 3 Pro (driver: 1.0.19, firmware: 1.0.3)
Processor: Intel Quad-Core i7-2600K Sandy Bridge 3.4GHz
Motherboard: ASRock Z68 PROFESSIONAL GEN3 LGA 1155 Intel Z68 HDMI
RAM: 32 RAM (4x 8GB of 240-Pin DDR3 SDRAM)
Hard drive: only SSD drives (SATA 2 and 3)
Windows 7 Professional