Yes it is, is has Sub L+R, Front L+R, Rear L+R.
Looks like more research needed.
I am pretty sure the sub connector isn't an RCA to the standard Bose it is part of the loom... I am sure I had to splice an RCA connector onto it and then you can plug it into either the L or R shouldn't make a difference which.... I stand to be corrected though as it was over 2 and half years ago I am absolutely positive I now have an RCA to the Bose Sub/Amp as when I fitted my Sub in the boot I remember swapping them over to hear the difference