Insight on different HomePod volume levels

Guys, today I played the ‘Placebo’ album at max volume on my HomePod and realised the following…

  • If I play directly from the HomePod via my Apple Music subscription OR stream from my Mac / iTunes library (via the Porthole app/Soundflower) then the sound levels are identical but for this album seemed a little lower than the max volume I have experienced from the HomePod with other artists/albums.

  • If I connected my iTunes library to the HomePod via Airplay then the volume levels were a decent amount higher and much more in line with what I have experienced with my HomePod previously at max volume.

All volume levels were are at max at all times - iTunes / Mac / Porthole (Soundflower)

Any feedback/ideas/insight?

I bought a second HomePod thinking that the pair would provide better sound than our TV. In fact, the maximum volume (from our AppleTV) is too low, and we went back to using the TV speakers. The volume for music is much higher. I hope this will be fixed in tvOS 12.