Comment by seba_dos1

Opus - perhaps, but claiming that 128kbps Vorbis is transparent would be rather stretching it (unless it's a mono stream); though how easily it will be detectable depends on the kind of music used to test it. However, if you added, say, Bluetooth A2DP to the mix and made it go through a lossy encoder again the difference should be pretty obvious to anyone with good ears.