I've got three stereo sources and one set of speakers. I don't want to switch inputs, I want all three to be mixed together and play at the same time. Is there any cheap way of doing this? Eg <$100? One of the items is a Boxee I use to play movies/tvshows off a fileserver. Is the best solution to get rid of the Boxee and replace it with a HTPC-lke setup and put in some soundcard with multiple inputs? Let computer act as mixer?