Objectives: to form a collaborative production process between the engineer and the band, so that progress is made via constructive feedback.
All tracks have been loudness normalised to a similar level as currently used by Spotify & YouTube to set a fair comparison. This is a fairly recent change in music streamming, which may be the beginning of the end of the Loudness War.
The above means that you can open those apps in parallel, set their volume to max and compare (roughly) to the mixes. Use the main master control in your system to turn the music up / down.
This player allows for switching across tracks by clicking the play button. E.g. you can switch back / forth between tabs to compare versions of the same song.
When sending Feedback via the form, pls state the system you used for listening: phone, tablet, headphones, large speakers, car, etc; so that I can get some context. Have fun !