hum, all i found was: "The Cowon Plenue D is powered by a TCC7901 SoC from Telechips and it is paired with a Wolfson WM8998 as its DAC component"
not sure if that helps tho, it certainly does not help me.
anyway... i think it was great if rockbox would support newer players. plenue d would make such a nice target, being small with great battery and having an sd card slot.