Duncs site does mention that the Source:One is a core (and by inference so is the Source:Five). It's not entirely clear from the data sheets however.

I'll keep digging.

Edit: the Sooloos Sourceless QuickStart Guide on Duncs' site confirms all Source components act as Core

Sooloos, Roon, G series (with LPS upgrade), 800 series (with LPS upgrade), HD621, AC200, Prime and PS, DSPs old and new.

Purdeys, Moke, Leica, 'Blad. Only the best.