[Fadem]

I am upgrading from my Samsung Galaxy S4 mini, which isn't much of a source to begin with... I'm looking for an Android phone; combined with a compatible DAC/Amp (if needed) which can be pocketable. Budget: $735 (€600). I use IEMs mostly; I will be getting a custom pair soon (Unique Melody Merlin), so I figured it's a good time to improve my source as well. I have just a few requirements:

1. Good sound quality
2. MicroSD slot on the phone is a must for me.
3. Non-audio, features, such as camera quality and screen resolution/brightness are important.
4. I'm currently using PowerAmp and I quite like it, so if I don't need to install USB Audio Recorder PRO, then that's a plus for me.

I understand if you were to recommend a Fiio X5 or similar product, however I am not looking for a DAP; help is much appreciated!