With the Space Duel harness in the Grav cab, you'd still be limited to 2 speakers but you could play Grav, Space Duel, and Black Widow all in the same cab if you have the panels. Using the adapter, the SD panel will play Grav so all you have to do is swap the board and add/remove the adapter. Alternatively, you can reorder the pins on the plugs of the Grav and BW cp's to plug into the SD harness directly.