I'll answer your questions first, then provide a bit of a further update.
I don't have Foobar or Winamp, but I have got the VLC player and Quicktime player, neither are sending sound out to the Fireface either.
Haven't attempted to install Cubase(my favoured sequencer) yet, more on this later.
My studio machine is also not hooked up to the internet, the studio premises doesn't have a connection, and I don't really want to risk getting a virus in my system, so its closed. So, all new software has to be registered on a separate machine, and unfortunately I can't use windows update to get the latest version of WMP, although its a brand new machine, its pretty much the latest version thats on there.
I could download the latest RME driver from their site, but I was using the Fireface with the driver on my old system and it worked perfectly for nearly 4 years. I figured if it wasn't broke, why fix it?
So, thats the full back-story, here is the latest;
I went back into the studio today, to try some other stuff. I've now totally disabled the internal Realtec card, it kept reappearing as the default sound device in the control panel(weird!) - I disabled the device, uninstalled the related software and deleted the drivers, then disabled the device from the hardware properties tab, that finally seems to have gotten rid of it!
Having done all that, and rebooted yet a again, I played an MP3 and to my suprise, it started playing! Then I had a repeat of that strange occurance - I clicked on the total mix screen, to see the audio going through - I briefly saw the audio coming out of outputs Analogue1+2(as directed) - then it suddenly stopped. WMP continued to appear to be playing the track but no more audio reached the outputs!
I rechecked everything again, the audio settings in the control panel - the default output for WMP, etc, I rebooted a few times, still nothing.
I gave up at that point and decided to proceed with plan b, I unpluged the fireface and took it home to reconnect to my old machine to see if there were any settings that were in any way different. The only thing I could that was different was a) the output volume and the fact that I had the ouput set as SPDIF instead of Analogue 1+2.
I dunno, I expect I'll head back into the studio, try these last couple of settings, if that works then great, if not, then I'll uninstall the faceface, drivers and software, then reinstall again. Maybe its something to do with me not properly disabling the realtec card before I installed the Fireface?