You could attach 10 amplifier modules to a single SMPS power supply if you wanted to.....as long as you don't exceed the power rating of the SMPS supply. And, of course, you have to be inside the nominal voltage range of the multiple amplifier modules...if they're different.
I currently have five UcD180ST modules attached to a single SMPS400A180 supply and it works fine.
Cheers,
Dave.