Just to confirm, the Stream Magic 6 is compatible with FLAC/WAV/ALAC files up to and including 24-bit/96kHz resolution via UPnP and local USB media. When I say local USB media, I am referring to the front and rear type A USB connections, intended for use with USB hard drives, memory sticks, etc. Here, the Steam Magic 6 is performing the decoding and playback of highresolution CODECs.
With this in mind, as you have seen, I can confirm that the Stream Magic 6 will not play back 24-bit/192kHz files via UPnP or local USB media (USB hard drives, memory sticks, etc). This is stated in the specifications of the Stream Magic 6 which are available in the user manual and on our website.
The USB Audio input is a different connection entirely. This is the type B USB connection on the rear of the unit. The USB Audio input is simply a digital audio input (like the S/PDIF input) which will allow you to use the Stream Magic 6 as a high quality DAC and input up to 24-bit/192kHz files from an external source - i.e. your computer. Here the computer is doing the decoding and playback of the high resolution CODEC and the Stream Magic 6 is simply performing the high quality digital to analogue conversion.