I have run HO and O scale smoke units on a QSI Titan Magnum. I have also run an HO smoke unit on a Loksound L. It's only 4 wires then program in the software. The Loksound XL also supports the Loksound plug and play O scale sized smoke unit. The 21pin Loksound HO decoders have an aux I/O board that you can purchase that allow them to control smoke units with 4 wires as well (2 for heater, 2 for fan) Doesn't have to be so complex really. There are lots of choices.