I don’t know if this will help (or make any sense for that matter) but I have a midi controller keyboard (M-audio Keystation Pro88 but I assume it’s the same with most midi devices) which can connect either by USB or standard 5-pin midi cables (1 in/1 out). Since connecting via USB means that I’m using the “USB<=>midi interface” which is built into the Pro88, turning off the keyboard also means that the “USB<=>midi interface” is also turned off and you get the problem you described. However, I bought an “ESI Midimate II cable” which, as long as it’s plugged in, is always “on” (and I’m sure the power usage is negligible) so I can connect my Pro88 using a 5-pin midi cable. Thus, as long as I leave the Midimate connected I can connect/disconnect or turn the keyboard on/off whenever I want without having to restart Cubase.