For MS-1 Music Server owners, Windows 10 64bit OS upgrade worked on my chassis here with improved sound results. The only thing I have noticed is that my BluRay player for ripping CD's is no longer talking to the OS. That maybe a registry issue I am working on, but will most likely not effect the original DVD drives most folks probably have.
Since the free upgrade from Windows 7 to Windows 10 64bit OS expires in June 2016, you should decide soon if you are going to try it. You can go back to Windows 7 with tools Microsoft install. The upgrade process takes about 4 hours on the MS-1 chassis.
My suggestion is to backup anything you have added to your MS-1 along the way and then do the upgrade. It will keep your files and programs, but certain default settings like Power Management get reset. That is an OS level change that I make to turn off the sleep mode and not disable USB power ports for low power operation. Easily corrected by the user under Control Panel, that is now a right click on the Start Icon.
For one MS-1 I am upgrading, I will be adding Math Audio Room EQ to Foobar2000 for the customers trials with his ACA LS-9 speakers being modified for a dspMusik digital crossover. I am installing all the software along with the Windows 10 OS upgrade once it arrives.
Good luck and let me know if you have any questions.