I don't think the AC components use channels? The Aquabus is serial like USB so you can daisy chain them. If the AC D5 has onboard memory like the Farbwerk the yes, you need to use USB first but I wasn't sure that it did (not used one of their pumps before). The USB is used to set the onboard memory to use an external controller (i.e. Aquaero) via the Aquabus but this should only need to be done once/initially. If it's like the Farbwerk, when connected via USB it appears as its own device in the Aquasuite. Once it's under Aquabus control the it appears within the Aquaero sub-menus.