You hook them up through your audio/interface either by a balanced 1/4" cord (or unbalanced like I have the hookup to my stereo system) or through a cord that has the ends on it for your audio/interface and either XRL input or like said, some even have a phono input (like for a stereo amp). Just have to look at the back of the unit also to see what it has.
I am using balanced cords even though I have an adapter to phono at the end for my stereo amp and speakers and XRL whatever type microphone connection on the other end. But of course with my audio/interface I have a second headphone output (mini-plug - 3.5mm like a small headphone jack) and use a cord for that to my cheap computer speakers (that for most things do not sound bad at all - plus they have a volume control because videos and music vary sometimes too much in volume, although I can do it a different way through the audio/interface program on my computer (totalmixfx from RME).
Just standard connections mainly and or an adapter if needed.
Studio monitors should be easier to hook up perhaps depending on your audio/interface.
But it all works nonetheless.
On that soundcloud link you can read how they recorded all the speakers also at their website. They had mics at 18" for each separate speaker system and made all the recordings the same.
I would have preferred having the mics at the 1 meter away to record the speakers but then I do not have the means to do it anyway.
Too bad they did not include even more speakers but then it was a year ago or so now anyway.