i am very fortunate to have a high end home theatre (a lifelong hobby). I have a processor and two dedicated 7ch power amplifiers. All up I have around 5,000 watts RMS power output and very high efficiency speakers (98dB @ 1w/1m).
even with this relatively ridiculous system, I can confirm that many viewings of material from the original Apple TV 4K is low in volume and I have to turn my system close to “reference” level. That volume in my room is normally enough to warrant the neighbours to call the police. But with many shows and movies it’s normal listening volume.
I do experience vast variations in output level from show to show and app to app. Apple Music in stereo is loud as heck and applicable to the volume setting on my processor. Switch to spatial (Dolby atmos) and it’s substantially softer.
Disney+ requires +10dB in volume to reach the equivalent volume of a bluray and some shows on Apple TV iTunes movies. Even then, movie to movie volume is very inconsistent even from iTunes movies.
now, having worked in music mastering and engineering, I can attest to the fact that some studios and their mixing engineers just make different sounding mixes. Some are soft, some are loud constantly, and others are correctly dynamic with very loud segments coupled with gentle soft sections and room in the mix to breathe.
So you will always have to endure some degree of remote control hockey while you adjust loudness to suit the material.
However, on a more technical note, there could be something with the output voltage of the HDMI output on the Apple TV’s audio interface. The voltage simply could be too low. Or, the software could be sending a cold signal into the hardware. Only Apple knows.
I too would love if Apple could put some energy into tweaking this.
