No, DAPs are not designed to work with low impedance IEMs. They are designed to work with high impedance small portable headphones. They figure if you are going to plug something in that requires amping, you'll have an amp.
Why do people insist on using IEMs that the DAPs weren't designed to be used for, and then blame the DAP for having bad sound? If you want to use IEMs just patch into the line out and plug in an amp designed to work with the IEMs.
The "sound" of a DAP is what comes out of the line out. The impedance is a function of the earphones.