One of these for sale, owned for approx 10 months : https://hdplex.com/hdplex-fanless-500w-atx-linear-power-supply-with-modular-atx-output.html

No DC DC required, as you can see its all built into the unit.  Plug and play.

I have managed to lose the XLR cables for LT3045 DC outputs (priced accordingly), but these can be obtained elsewhere.

Great condition otherwise, have original packaging and all the other cables (silver OCC + extension etc).

£475 + p&p (can ship international or EU, just bare in mind its a 17-18kg package).