Okey so enough of PWM for audio, its time to get serious ! So i fired up Altium again and went on designing a proper sound card for the XC-2, and quite a sound card it is with its capabilitys reaching up to 192Khz at 24Bit. Still while packing a punch it remains quite tiny at 25×40mm only and half of the room are the big 3.5mm jacks. There is also a small 8 pin oscillator on the board that provides the necessary clocking to the DAC/ADC chip. The thing can be configured over SPI, I2C or hardwired setting on power up. I2C is also used to change the system clock if needed as the oscillator has a I2C port.
Note: I have no built this yet so its not verified that it works!
Bigger images on my blog post: http://thexmoschallenge.wordpress.com/2009/12/17/sound-card-pcb/