So my librewolf config has 23 color-coded containers with rules for various websites I use.
Which actually, maybe it's just my OCD because that's probably possible with the different icons for the stock multi-account containers add-on. But I made mine be all just the solid circle icon and a unique color for each because I wanted it color coded. Which I guess is a little OCD brained but
Also made the letterbox black.
If anyone's interested I can share the mods
Playback device is a much bigger difference than lossless vs. mp3. If you think you're getting a subpar experience, another thing you can try is listening on some different headphones with different frequency responses.
I put .wavs on Bandcamp for my music though -- sometimes artists put higher fidelity files on the pages they more directly control. Rather than ripping an mp3 off youtube.