I have an RME Fireface 800 and Wavelab 7.
How would I record in Wavelab, say a song played back by a media player, or music streamed/played back from an internet radio station? Since the sounds are coming from the PC itself, I wouldn’t use one of the FireFace inputs, but how then would I do it?
While you’re waiting for a more useful answer …
I can’t answer your question in terms of your specific hardware, but, FWIW, one “last resort” method of recording streamed audio is to use physical patch cords to route the (analog) output of a sound card back into (analog) inputs (making sure you don’t create a feedback loop, eg via your recording software). You then make a recording just as you would from any source plugged into the same (analog) inputs. Of course, this won’t work if your sound card can’t be used by the two different programs at once.
In Windows you need to set the Recording device to ‘Stereo Mix’.
Eg in Windows 7 right click the speaker icon in the systray, select ‘recording options’ and then select ‘Stereo Mix’ from the list. (If that option doesn’t appear you have a problem with your general audio setup.)
Is that necessarily true?
I see that, on my audio PC, which has an Emu 1820m for sound, “Stereo Mix” isn’t available - just an Emu option.
“Stereo Mix” also isn’t available on my internet PC. I think that’s because that PC has an Emu 0202 USB for sound, plugged into one its USB sockets. I might try unplugging it some time to see whether doing that on its own can make “Stereo Mix” become available - but that wouldn’t be an option with anything like my 1820m, which has a card “permanently” inserted in the PC.
I have, though, successfully used the way I described in my post above to record sound streamed from another program, on my internet PC. I don’t have Wavelab on that PC, but see no reason why that method wouldn’t have worked with it.
Yes, TotalMix is your friend.
Be sure that your ‘Windows Sounds’ are routed to a pair of FF’s playback channels (via control panel/sounds). I send them to S/PDIF usually as I don’t use these channels for anything else. Send them to a pair of FF’s output channels and use the loop back feature of TotalMix there (instead of hardwiring ins + outs which is a little '90s 
). Loop back is activated by Alt-clicking the labels (or maybe Shift+click - can’t try atm), they have to light up red.
The loop-back activated channels now turn into an input signal that can be used to record them in another software like Wavelab.
^
Just to be sure …
TotalMix is a utility for use only with RME soundcards, is it? (Not usable with (eg) my Emu 0202 USB?)
adding to the answer of using “Stereo Mix” :
Under the tab “Recording” do a right-click and make sure that option “Show Disabled Devices” is checked.
Do you see your “Stereo Mix” option now?
Yes, TotalMix is RME’s mixer software for all devices.