Yup. This. The screens are killer. I love my FiiO BTR5 because it's screen isn't color or large. Granted it's not a DAP, it needs a phone which there ya go - limited battery life.

The other thing I think that drains the battery here is the amp part of these devices. Some can deliver a decent bit of power and that costs a lot of juice.

Running android isn't a very battery efficient thing to do. Though it lets you install all sorts of apps. So it's convenient. People want Qobuz or Tidal. So that's what companies need to do in order to sell to those customers. That by nature means battery life is going to be tough.

I think if someone was really smart - they'd build a very stripped down operating system of some sort that could run Roon and have that tap into online services or pull from the network. Really optimize on battery. Even still though, it'll be tough to get back to 40+ hours I think. "All day" (which sometimes isn't even all day - certainly not after battery life starts to wear) is the only real target most devices have these days. Phones, laptops, audio players or otherwise.