You're going to have some lateral distance to cover. The 990's balanced outputs are on one side, and you're going to have to reach to the opposite side of the rack for some of the 7700's inputs (which will be almost .5 meter all by itself, without taking into account bends at the connectors). I'd recommend 1.2 meter for most of the runs, although .5 meter might work for the couple of amp channels that are straight down.