Yes, I've done some ABX listening tests to find out about my point of transparency.--bitrate 96 is transparent to me for the vast majority of even critical samples. If you ignore these you can go even lower.There were samples that weren't totally fine using --bitrate 96. With one exception even they were transparent using --bitrate 128.The exception was a harpsichord sample, harp40_1. Even this is acceptable using --bitrate 140. harpsichord music can be a special problem to other lossy codecs as well, for instance mp3. As long as you aren't much into this genre I would ignore it when it is about struggling for transparency. As you know what are harpsichord music tracks you can use very high bitrate for these.
I am waiting for my favorite Poweramp smartphone music player to support Opus and especially Opus replaygain.
The dev builds of poweramp are not available to the public. Your only option is Foobar.
God damn Opus is an amazing codec, I hope it continues to improve - although I have no idea how much further it can be pushed. I remember thinking transparency at 128kbps would be an amazing achievement.
I never noticed any artifacts at 80kbps though, though I haven't tried to find any either.
I tried it and for me it's 80 kbit.
I'll be honest, I struggled to ABX at 64kbps. 80kbps is enough for me.
80kbps is pretty much my limit as well, can't be bothered listening to killer samples all the time.