I googled for about 10 minutes, theres no fucking specs on these anywhere.
I've heard that these have a High output, I've also heard that triggers have a very low output.
In any event I'd xlr to xlr. If they are too loud, you can pad the preamp. If they are too quiet you can turn up the gain. If it was line level there isn't any gain staging unless you run it into a mixer, but then you'd need 2x more cables.
Mic level, xlr to xlr.