Audio questions : i2s, dac, oversampling, PIC, FPGA ...

Hello,

I have a board with an embedded PowerPC (mpc8241), on which there is no audio hardware. I want this board to have audio capabilities. I have serial ports, usb ... but no i2s, which is, from what I've understood from my previous readings, the bus needed to control a DAC.

I'd like the sound data to be oversampled to 192kHz. (let's say I have a HDD connected to this board and it contains 44.1 kHz PCM data files.)

Actually my idea is to do smthg like :

MAINBOARD == i2s ==>(OVERSAMPLING?)===> DAC ===> Analog output

with mainboard separated from the rest of the hardware, in order to be able to plug to it High-Fidelity/High-Quality Audio-DAC

So my questions are :

1. Where the oversampling must be done ? in processor ? with a dedicated hardware ? Before being sent to i2s bus ? after the firts device (DAC?) on i2s bus ?

1. How can I get this mainboard to have i2s capabilities ? I've searched a bit, and I think I've understood I should use a dedicated microcontroller (PIC ? FPGA ?) attached to the main microprocessor. True ? If I have an i2s bus, can I have the audio DAC separated from main board, just linking them via the i2s wires ?

2. where can I find some good quality Audio DAC kit, taking data from i2s bus, sending Analog audio to RCA plugs ?

Thanks

Yann