I may be wrong, but I think you are going to need a streamer of some sort going into a DAC to make Quobuz work. This can be a computer set up or dedicated streamer. Right now you are using the DAC inside the iphone. When you remove the hard wired connection of phone to preamp, you no longer have an interface for Quobuz to stream to.
Others will certainly chime in with thoughts, but that's mine.
Oz
Others will certainly chime in with thoughts, but that's mine.
Oz