SaltPlayerSource VS Music-Player

Salt Player has compressor for making quieter parts of music lower and vice-versa

You can try Salt Player if you want features like Synced lyrics at its best and also dynamic light flow, just give it a go

Salt Pepper Music Player

You can try Salt Music Player Although it doesn't have the features you stated but give it a try

Although the app I'm suggesting doesn't have player overlay on lockscreen, the Now Playing UI is awesome, if you're fan of features like dynamic colour flow, and beautiful lyrics UI, you can use this Salt and Pepper Music Player

You can use Salt Music Player Github

You can check FLAC files quality on PC using a program called spek, also musicbee can show you track information for eg. 16/24 bit FLAC, 44.1/48 kHz 1620k, stereo and on phone I only know of Salt Player that shows information like this. Salt player is very powerful but it's Chinese. Available on PlayStore, github and their telegram channel. I love this player but don't understand their privacy policy and they've got Chinese sponsors too. That means it's not good. Privacy policy (Translate it to english using some extension)

Metro is good , but I'd pick Salt player anytime https://github.com/Moriafly/SaltPlayerSource

My setup is some cheap iem and mid range headphone, on android i use Apple Music, Salt Player for offline music, and CloudPlayer for my cloud library.

For me the metro app completely broke on me. My playlists disappeared after an update, the backup function wouldn't work, and after I reinstalled it in an attempt to fix an issue, it wouldn't detect my music files. I've since called it a lost cause and moved onto another music player. I've tried many of them and found that one called Music works the best. It's got the basic features and a decent UI.

According to https://github.com/MaxFour/Music-Player "Music-Player" is based on a https://github.com/kabouzeid/Phonograph version of 2019

Maybe Music works, it looks like it had changes made for Android 11.