Dual PSU for XA252 POP in external case

My plan is a dual mono PSU in an external housing. The background to this is that I'm penny-pinching 😎 and want to compare several amplifier concepts, and if I have to install the PSU every time, that's really expensive.
I have 2 Toroidy Audio Grade Transformers with 2x18V and 300VA. I would install a COMPACT CRC PSU from Prasi for each channel with the LT4320 bridges. What do I have to pay attention to? Does a capacitor bank also have to be in the amplifier housing?
What about the grounding?

Best regards, Eddy