I bought Primus A25 . Before I read about problem with midi-controller at Studio One 4. You need go to standart Panel of Devices in Windows 10 , find Unknown midi device , and then manually install driver from the folder , where you downloaded official win7_x64 audio-driver. It will be installed. So you have working midi. At Studio One create new device and set channel of midi input to Port 2 . :)