I think I have a manual and can copy and send to you. I am pretty sure you only need the pin if you are connecting to a preamp (other source) that has only RCA outputs.
I honestly staggered the amps about the width of the overhang of the front plate and was able to put on my rack. If you are able to put them on the floor, though, you can get very short speaker cables for better sound.
I suspect Ralph may chime in and correct any mistakes I stated lol.