How do I do this? A new diy twin tda1541a dac is on the way (partially assembled tube-lover's kit). His design makes use of cs8412 digital receiver. In addition to a spdif BNC input, I want to modify this dac to add a USB interface using pcm2706 digital receiver. This IC is capable of receiving USB (and spdif) and outputing I2S to the twin tda1541a IC's (which are capable of accepting i2s input).
I would build a small daughterboard with the 2706 interface with separate battery power supply so that it is not bus powered (total of about 7 parts for this board). This interface has been built by other diy'r.
So if I want both BNC spdif input socket and usb input socket on DAC, how do I best accomplish this? Here are possible options
a) Only use the 2706 digital receiver; both for spdif input and usb input. It would send i2s to the tda1541a's. But I would need some type of switch to do this? Also, would I have to de-solder the cs8412 IC that comes installed on the dac pcb?
b) Use both the cs8412 (for spdif interface) and the 2706 board (only for usb). How would I do this if I want both 8412 and 2706 to send i2s signal to tda1541a's? Can tda1541a receive two I2s signals? If this configuration is possible, how do I switch between spdif and usb inputs?
I am concerned about taking the cs8412 out of the design: (1) because most of these tda1541 dacs use this receiver; and they must use it for good reason and (2) I am paying for the part and attendent caps, power supply etc.
How best can I accomplish my goal of adding the usb interface?
Here's photo of dac pcb...

I would build a small daughterboard with the 2706 interface with separate battery power supply so that it is not bus powered (total of about 7 parts for this board). This interface has been built by other diy'r.
So if I want both BNC spdif input socket and usb input socket on DAC, how do I best accomplish this? Here are possible options
a) Only use the 2706 digital receiver; both for spdif input and usb input. It would send i2s to the tda1541a's. But I would need some type of switch to do this? Also, would I have to de-solder the cs8412 IC that comes installed on the dac pcb?
b) Use both the cs8412 (for spdif interface) and the 2706 board (only for usb). How would I do this if I want both 8412 and 2706 to send i2s signal to tda1541a's? Can tda1541a receive two I2s signals? If this configuration is possible, how do I switch between spdif and usb inputs?
I am concerned about taking the cs8412 out of the design: (1) because most of these tda1541 dacs use this receiver; and they must use it for good reason and (2) I am paying for the part and attendent caps, power supply etc.
How best can I accomplish my goal of adding the usb interface?
Here's photo of dac pcb...