I am in the process of building a DCC test track for our local NMRA division.  Being a HO Scale modeler, I have come across an issue I am nor sure about.  Z-scale motors are run on 9 VDC while N-Scale and HO are run on 12 VDC power.  When we apply DCC electronics to them, what is the power output?  

I don't one want to burn out someone’s Z-scale DCC decoder by applying the wrong voltage to the unit.  Does my DCC system (MRCProdigy Express) adjust the power output, or the fact that DCC uses square wave alternating current change the whole paradigm?

MRC has suggested that it should not make a difference and that their system will run all scales, but I would like a second opinion that I can understand.
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RicZ