I am trying to figure out the circuit board located in the tender of my Durango & Silverton to put sound into it (it already is DCC), and I searched but have not found an answer to this easy question. The circuit board is hard wired to the tender plug and then there is an 8 pin, plug in board, connected to that board. Can I remove the plug in board and plug in another decoder?  Does the other board need to be both DCC control and sound, or can it be just a sound board?  Or do I have to remove the electronics completely and put in a combo board?  From the fact that the secondary board is the standard 8 pin connector, I would think that this is where a decoder board might be installed (replacing the current board). Thanks.