Good. Here is the graph of conducted emissions on Hot input lead:
View attachment 8385
You see all those spikes? They are below the level needed for regulatory agencies but no way are they a ticket to put that line right next to the DAC output where we want to resolve better than 20 bits of dynamic range:
Here is your box again:
View attachment 8386
You see the circle in yellow? You have to keep the signal wires in white away from switchmode supply. They will bleed and your friend here is distance.
The mains switching noise may evel leak onto the DAC board, your DC regulator, buffer amp, etc.
You have no business creating long paths for AC cable of a switchmode power supply and snaking them everywhere.
Now, this may all be fine if you had measured it and knew this leakage does not exist. But you have not done so.
You are blindly going the wrong way on the road and whistling happy. No professional DAC designer would make such obvious mistakes, violating simplest rules of good hygiene in electronic design.