Universal iOS Music app with volume normalisation

[mgpg89]

Hi all,

I'm looking for a reliable iOS music app with the following functions:
- Apple Music support
- reliable volume normalisation
- nice to have: automatic start/stop at certain preset times

Currently we have Sonos speakers in our stores but the volume levels of the tracks in our playlists don't match.
Sonos doesn't offer any normalisation when using Apple Music, either.

That's why we'd like to hook up an iOS device to the aux-port with a third party that brings the volume of all tracks to the same level.

Any help would be greatly appreciated.

Kind regards