Impossible to adjust volume level of local files on Android

[DroidFreak36]

Plan

Premium

Country

USA

Device

Moto G5 Plus

Operating System

Android

My Question or Issue

I recently started the Spotify Premium trial on the recommendation of a friend, with one of the major selling points being the ability to upload local files to Spotify for listening on my devices. So I already have over 1000 local files added to a playlist. The thing is, the "Normalize Volume" feature doesn't work on those local files. Which is completely fine by me since I don't want to normalize volume anyways... except that there's literally no way to adjust the volume of the Android app (relative to other apps) without using that feature.

This is probably a deal-breaker for me. If I can't adjust Spotify's volume to be less than the full media volume level (to balance it against other apps which use the media volume), I'll probably cancel premium and go back to using a local media player.

By the way, I have tried the equalizer, but there's no way to set the equalizer to a flat reduction of volume. Unless I could somehow replace the equalizer, that's a dead end.