Decided to make sure everything was working, XSplit wanted to do an update and wouldn't let me proceed without doing it... so I downloaded and installed it.
Now when I start the stream I get an error message saying the Stream was stopped due to unsupported audio codec. I've gone in to general settings and ticked the "Use WinXP Sound" but it still does the same thing.
Anyone come across this before I hit the forums/Google to see if I can work out what is going on? They do say that the update was resolving some sound issues and had more to do with Win 7 users (which I'm using)
EDIT:
Just in case anyone else runs into this, all that was needed was to remove my Twitch channel from XSplit and put it back in again.