Multiple MECs and UseHouseSync=1
PARIS is unable to operate with more than two MECs attached without both enabling Word Clock and using an external clock source (aka "house sync") to provide them all with a common "word clock".
Word clock generators must be purchased separately. There are various commercial options for external clocks, such as Lucid or Aardsync products. One new contender which looks promising is the Black Lion Audio MicroClock.
Some audio cards such as the RME HDSP 9632 and HDSP 9652 can generate two wordclock outputs using a daughterboard.
In order to use an external clock to enable multi-MEC functionality, the paris.cfg file must be opened with a text editor (change the file extension from .cfg to .txt), the following line inserted:
UseHouseSync=1
It is essential to set your DefaultPpj Default Project.ppj to a samplerate of 48k, which the MECs must see at initialization in order to start up properly. You can switch without problem to 44.1k after the project is open.