I agree the RCA output needs to be on the other side. But you don't need USB audio player pro to play music, you can use instead the free app HibyMusic ( https://play.google.com/store/apps/details?id=com.hiby.music ), which covers the missing drivers in similar way.
iFi Nano iDSD does not have Headphone Amplifier, the volume wheel uses attenuator for both R/L and headphone port.
But you don't need USB audio player pro to play music, you can use instead the free app HibyMusic ( https://play.google.com/store/apps/details?id=com.hiby.music ), which covers the missing drivers in similar way.