I have absolutely no trouble getting Roon to recognize my computer speakers/Meridian DAC on a laptop running Windows 10, but why is it not recognizing both on my work computer running Windows 7? Perhaps the latest version of Roon is incompatible with Windows 7? Please see attached.
I run Roon x64 on both Windows 7 (work laptop) and Windows10 (home PC) without issue.
I would suspect a firewall issue on your Windows 7 machine. Are you able to configure it?