It is easy to build a DAC with S/PDIF inputs and very high performance analog outputs using DAR 18 and W-DAC. More inputs or balanced outputs can be added with stackable addon boards.
See above a photo of DAR 18 prototype connected to a W-DAC prototype.
All four I2S signals (MCLK, BCLK, WCLK, DATA) between the boards are easy to connect with U.FL cables. Just pick a suitable length.
Other signal connections
In the photo above we have connected mute with the yellow/orange cable (one of them is ground which is strictly speaking not needed as there is ground in U.FLs already and this is a static signal). This engages hard-mute on the DAC when S/PDIF input is not locked or not suitable audio.
The photo above uses HW-variant of each board. However, if I2C variants are used, I2C (SCL, SDA, ground) is also needed with a host processor that programs the registers after power-up. As I2C-variant of W-DAC supports volume control, a full digital-input preamplifier can be implemented to drive a power amplifier or active speakers.
DAR 18 only needs 5V VD supply, while W-DAC requires three or four supplies (see W-DAC guide for more details). You can use your own power supply and solder wires or modify shown Molex cables for your needs, or you can use upcoming Kaamos power supply with easy power connections.
PCM input source
If you wish to use additional source with PCM/I2S output, such as a USB-module, connect it to PCM input header on DAR 18.
Please read following to fully understand the functionality of the boards: