Bi-wiring means using separate runs of speaker cable to the HF and LF terminals on a loudspeaker. The intention is to gain some of the benefits of biamping (where each driver is driven by a separate amp) at substantially lower cost. There are two methods of biwiring from Cambridge amps.
The first is to connect both LF and HF runs of speaker cable to a single set of terminals on the amp and run them to their respective connections on the loudspeakers. With some of the smaller Cambridge Amps, this is the only option as they only have a single set of left and right terminals.
The other option is to connect one set of cables to speaker A and the other to speaker B and run them to their respective terminals on the speakers. This has the advantage that 4mm plug terminations can be used on the cables and it can often be easier to wire a single set of cables to each set of terminals. In all cases you will need to ensure that both speaker A and speaker B are selected.
For information regarding the benefits of Bi-wiring please view the Blog post here.