If I am correct, my understanding is that a sound decoder with factory sound files will become available at some stage. I am sure that those who were not quick enough with the models already sound fitted will be welcoming this.
Roads and rails are offering this already, however the ESU passive radiator speaker may be out of stock (for now).
There is an alternative offering from DC Kits, which has been developed specifically for the Cavalex 56. This appears to have covered most of the existing functionality of the factory sound project, in particular the lighting options, but with differences leaning towards their usual format.
Has anyone gone down the DC Kits route? I would be intersted to know how the sound project compares.