Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
The best sound decoder for this engine is the SoundTraxx Tsunami Heavy Steam with a 20 x 35 mm Medium-Oval speaker mounted in the Speak EZ 20 x 40 mm Medium-Oval Enclosure; however, as others have already pointed out, you won't be able to change any of the sounds with the DCC system you're using, so the results will be disappointing.
As David says the EZ Command is the limiting factor.
You can install a sound/control decoder but you will be unable to change CV values because EZ Command does not permit it, the only exception being the address. If the decoder is setup out of box to respond to your functions 1 thru 10 you are ok, if not you can't do much about it unless you bring the engine to a friend who's command station can deal with the decoder CV changes.