My build progress

[fredrik]

@antoine.pasde2

the same phase of the AC must be applied to the inputs of the two Frequency Central boards

See illustration here:

Power supplies choices?

Yeah, you need to connect the same wart lead to the same AC input on all supplies. Like this: [B05725DE-9DF6-4E65-97A6-1DA29516B945]

(and this post for why)