Thank you for taking the time to post this information, much appreciated! I currently have a USB hard drive connected to the rear USB-A input and it plays DSD/DSF files just fine. My comment about the USB-DAC Asynchronous input and a USB-B input port. The M2 has it but not the M1.That is what I know about the 700. It is dated 2019, but this would confirm the device has a USB DAC.
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*sorry about the huge picture!