Lossy audio formats suddenly become very discernible once you subtract the left channel from the right channel. Try that with Lossless audio vs MP3, Vorbis, Op

Lossy audio formats suddenly become very discernible once you subtract the left channel from the right channel. Try that with Lossless audio vs MP3, Vorbis, Opus, AAC, etc. You're listening to only the errors at that point.