Wasn't gonna post anything but this room needs some traffic!
So my 10 years old Preamp only had Coax input, no toslink. Nowadays it seems all source components are mostly toslink.
So I bought a cheapy $15 bux toslink - coax converter form eBay (OK, not audiophile) and just hook it up right. No way. I don't want YET ANOTHER power plug, and yet another thingy hanging out the rear of my equipment which is already a spaghetti mess. I disassembled the the adapter, transplanted the components to my own PCB and fitted inside my Preamp as if stock.
It turns out the circuitry is relatively simple, the new PCB is able to accommodate 3 toslink ports. Am all set.