I save everything in mp3 128kbps. I compared the quality with higher quality and with my setup (Bose speakers & in ear headphones) and with my ears, I can’t hear a difference. Opus is more efficient but my source is already in mp3 and I don’t gain anything by converting it. If I had to convert from flac, I’d choose opus. 1 4k movie is so big, the size of music doesn’t really matter at all.

The only downside to keeping everything in a lossless format is that over the years new formats emerge. mp3 used to be the only game in town, but now we have multitudes of lossy formats to pick from. By having your collection in mp3 format, you aren’t able to say “hey, this new format looks cool, let me switch to that”. By storing everything in a lossless format (FLAC), you can convert for mobile as you see fit.

What could I gain from switching? Playing mp3 will always be there and even if support is dropped in 30 years which is highly unlikely, the server can transcode on the fly. I’m unfortunately/ luckily no person with ears that can hear a slight difference between losless and 128kbps