To be fair, with my older ears, all three of those formats at that level are transparent against any FLAC source I have yet to use. When you DO start to hear differences are at lower bitrates, as you have noticed.
Observatory skills trumps young age…
Off-topic: (bite me ;-)
I've noticed use of the 'transparent' moniker before. Usually at fora frequented by users that claim some authority on audio quality.
Personally I am sensitive to hearing sound artefacts. Or out-of-balance sound imaging. (room reverb/ambience etc.)
That's how I am sometimes (depending on the material) able to hear the difference between lossless and lossy.
The word 'transparent' sounds interesting indeed, so I understand people like to use it.
But I am not sure how 'transparent' sounds, and can be described.
I've had some unpleasant encounters on other fora where believers in the concept of 'transparent' said mp3 320 is 'transparent' already, and that I was imagining things when I thought and stated that I could hear differences between lossy and lossless. (again, depending on the material)
What does 'transparent' mean to you?
Good enough? Perfect? Good enough frequency range? No noticeable artefacts? What?
At this moment I think I have a dislike for the word.
Convince me otherwise?