standard soundcard : line or ...

Windows 7 - 64 bit

After the setup i see that the Yamaha has been added to the control panel (hardware & audio).
When i select audio, i also see Line - Sreinberg UR12.
For the moment Realtek (onboard) is set as standard.
Should it remain like this or …

I recommend that you leave the Realtek as the default for systems sounds, and only use the sound card for your DAW stuff.

This means that extraneous system sounds will NEVER break into your sessions. Just make sure that during sessions, you turn off the power to whatever speakers your Realtek drives.

Of course, you can temporarily select the UR12 as an output for your Realtek when you require it.