I've only been on CHN (0003) firmware for a couple weeks, and tbh, even given that I prefer to use low gain on this firmware (???? I know, I know, but it's true), and I also prefer to have High Res Streaming turned <Off>, I get pretty much the same battery drain as I did previously using International & JPN firmwares (with those I used high gain & High Res Streaming <On>.
Now, that said, I tend to get ~6% (+/- .5%) battery drain per hour of "normal" music playing (i.e., minimal screen use). I listen to ~90% 16 bit ALAC, ~10% 24 bit ALAC; 4.4 output, low gain, vol 70-75 (depending upon transducer used), High Res Streaming <Off>, Direct Source <On>
Now, that said, I tend to get ~6% (+/- .5%) battery drain per hour of "normal" music playing (i.e., minimal screen use). I listen to ~90% 16 bit ALAC, ~10% 24 bit ALAC; 4.4 output, low gain, vol 70-75 (depending upon transducer used), High Res Streaming <Off>, Direct Source <On>