Windows and its typical applications have no clue about ASIO.
Therefore you can provide WDM devices for windows in the RME driver settings dialog
(see symbol in the Windows info bar on the lower right) for all all analog and digital channels.
Under "WDM Device Configuration" you define
a) in TAB "WDM devices" for which I/Os you want to create WDM devices
In a 1st step maybe only for Analog 1+2, assuming you connected there your main monitors
b) in TAB "Speaker" which of those are speakers (Analog 1+2 in this example)
the latter you need so that you can select in Windows "sound" settings the default Windows output device
which usually is your main speaker.
Then change to Windows Sound configuration and ensure that RME UFX II Analog 1+2 becomes the standard output device.
All system sounds, Sounds from applications like Internet Browser which use the Windows Sound system will now playback sound via your monitors.
All sound coming from Windows you will see then in TotalMix FX in the Middle Row under Software Playback channels
in particular Analog 1+2.
Your routing you set best in TM FX "submix mode", see upper right in TM FX.
Click to the output channel Analog 1+2 in the 3rd row and then move the faders of
row 1 (your inputs of the recording interface)
row 2 (all that comes from applications)
Rest see my primer please.
TotalMix will usually be set (as long as you dont change it) to operate at 0dB.
This will be very lound for most of the Near Field Monitors.
1. if your main monitors have potis, then use them to turn down the volume so that even 0dB do not hurt too much
2. otherwise pls have a look at this thread: https://www.forum.rme-audio.de/viewtopic.php?id=25399
3. Assign in TotalMix FX your main output and set the volume to a comfortably silent start level, i.e. -20dB or -30dB
4. save this setting to snapshot 1 and rename it i.e. "main out"
5. save these settings to snapshot and workspace like I documented in my primer and eventually also into a Workspace Quick select slot
6. store this state eventually also into your device into the configuration slot 1 (out of 6 possible), then you can even recall this state standalone on the device if you want/need it. You can update this at any time.
7. Enable in TotalMix Preferences (F2) to alway init SDP devices with TM FX settings, then the device will be initialized with the snapshot settings to the lower output level
8. Get an ARC USB where you are able to mute quickly or to move the volume knob quickly (quicker than with mouse)
Win7/Cub9, Supermicro X10SRi-F, E5-1650v3, Sonnet USB3-PRO-4PM-E