The lower the bitrate the easier it is to tell the difference, that is no surprise. The question is if there is any point on the spectrum where lossy files cannot be distinguished from losslessly compressed files like FLAC. The BBC have done some research, and their conclusion is that at 320kbs few people if any can tell the difference. Of course, to test this, the method has to be double blind, and involve a sufficient number of repeats and participants to be statistically significant. However, all the serious reserach (rather than anecdotal) seems to confirm this. On the other hand, this will become increasingly irrelevant when bandwidth is getting cheaper and cheaper. The BBC itself is currently streaming experimental broadcasts of losslessly compressed 16/44 FLAC files.
Can you hear the difference?
Try this and see if you can tell the difference between lossless files and compressed. I got two out of the three correct yet I missed one even with my "young" ears. I'm using Sennheiser HD 650 phones on a modified MF headphone amp. The purpose of this fun little game is that Spotify is doing some testing with loss-less music. It's just something you can have fun with, would be interested in what this forum scored!
https://www.theverge.com/2017/4/5/15168340/lossless-audio-music-compression-test-spotify-hi-fi-tidal
https://www.theverge.com/2017/4/5/15168340/lossless-audio-music-compression-test-spotify-hi-fi-tidal