Supposedly the newer SoundTraxx products will meet the NMRA DCC voltage spec, but the earlier stuff does not. It's a shame that an American company does not follow the NMRA standard, since it's been shown in the last 10 years that given the wide variety of gear ratios and motors that you should run the full 24 volts to the rails, and decoders should handle 27 volts ( per NMRA specs. also.)