I have a DAC with a USB input and AES/SPDIF coax output (which plugs into a processor that likes that AES signal and runs natively at 48/96k). Which of themany new and old Apple boxes can send music to a USB port and on to my DAC?

I have a DAC-like device with a USB input and AES/SPDIF coax output. You see, the device plugs into a processor that likes that AES signal (and saves one stage of DAC that way). BTW, the processor runs natively at 48/96k. Which of the many new and old Apple airport or TV boxes can send music to its USB port and so drive my USB DAC-like device*?

Mostly the Apple boxes take iTunes and stream it either to an audio output or, in the case of older Airport Express boxes, to a SPDIF-optical jack. But I want to use a USB all-electric all-digital path.

Thanks.

*It's not really converting anything much, so not putting the audio signal through a stage of D/A... just converting the USB signal to SPDIF-coax.