Well seeing as you don't give the slightest hint about what the relationship between joysticks and motors is supposed to be, it's rather difficult to offer suggestions - other than what's with the DAC's? - sounds a very poor way to feed the motors?.
It is a poor way to drive the motors but unfortunately I don’t have a choice.
Sorry, I forgot about that. The relationships are given bellow.
joystick fwd: left motor=full fwd, right motor=full fwd.
joystick fwd right: left motor=full fwd, right motor=stop.
joystick right pivot: left motor=full fwd, right motor=full back.
joystick back right: left motor=full back, right motor=stop.
joystick back: left motor=full back, right motor=full back.
joystick back left: left motor=stop, right motor=full back.
joystick left pivot: left motor=full back, right motor=full fwd.
joystick fwd left: left motor=stop, right motor=full fwd.
However, they also have to be proportional e.g. with the joystick half forwards the motors should be motors half forwards.
I’ve been racking my brain over this for a while but I just can’t get it.
Thanks