I'll be the first to ask .......... why?
Windows 7 was a good OS, but despite it's occasional weirdness Windows 10 is stable and is the one the manufacturers of all the gear design their kit for. Older kit runs happily on Windows 10, and support for 7 has now gone, so if something doesn't work - you are stuffed. I happily agree that for a while, there was a point in keeping 7, but every time I start up, there will be an update for a Kontakt instrument, or a Cubase upgrade, or like a few weeks back a driver update for my interface which fixed the occasional loss of USB connection. You'll get none of this on 7, and at some point your favourite instrument or app will suddenly stop working and you are dead in the water.
I cannot think of a single reason for staying with 7 - unless you have a piece of old kit that you need and isn't supported on 10?