Hi elektrodorks 
in order to use the dir inputs with two monophonic synths without using the thru machines you need to get mono Y cables.
you may need to make them up yourself or modify an insert cable by shorting the tip & ring if you cant buy them at your local. u could get those cheap 6mm 2 into 1 adaptors but they are pretty shitty
of course this limits the OT inputs to two, but this limitation is elektrons questionable idea anyway.
feature request? pannable direct inputs anyone?