My experience with Android devices is mixed. On one side it is a way to avoid ground loops coming from PC, but there are limitations in the Android USB implementation forcing resampling on the phone. Only few payware apps will bypas system mixer and play in a native sample rate. I would typically recommend Audio GD DI-20, but in this case a DDC that does reclocking all the time (most of DDC's) might serve you better. This is not a recommended solution, as sound is already degraded. I would rather look for a quality DAP, these devices have a modified USB stack, dedicated for music playback. With a quality DAP as a source your friends would perhaps change their minds regarding whether DDC helps at all. An alternative is a network streamer, but is not free of ground loops, the same Rpi4.