I finished my case prototype of the SOHA-DAC combo. I know the cutting and wiring is shameful, but they are work well now. Next step is to find some good board and redo the wire.
There are two LED that indicate the source is coaxial-DAC or RCA line in. Now source is DAC.
On the top the metal net is a piece of officedepot's card holder.
The red board is the DAC, DIR9001+PCM1793. I got it from ebay. It used 12DC single rail input, and splited it into +-6V and virtual ground by LM1875. I removed the LM1875, and made a DC source on the yellow board, +-9V to the OPAMP, +6V to DAC, -6V for source switching and LED. Since the OPAMP is using the seperated DC source from DAC, I put the OPAMP, decoupling cap into another board. The opamp board is connected to the socket with pins. The two relays are for coaxial or RCA switching, and LED controling.