I recently purchased two K4003 amp kits and was wondering whether I can power them with a single let’s say 120VA 2 x 12V Toroid (12012). Or is it better/required that they will be powered by individual 50VA 2 x 12V. I guesss it should be okay, but I prefer to ask before I blow something up 
For best results, we recommend separate transformers.
Just out of curiosity, what are the negative effects of using a single transformer for two units? I’m asking, cause the units will become part of an art installation where the clarity of the sound is not the most important thing as it is used to resonate large metal plates (although I might want to repurpose the amps in the future).
In this particular project size is one of the most essential factors, so if I can use 1 transformer, I just might prefer that over best results. Thanks for your time and expertise!
A single transformer can lead to hum troubles if the wiring is not according to the rules of good engineering (risk of hum loops).