magni 3 amp

I think I'm going to get magni 3 amp and DAC! are quality DACs as important as amps?
im a noob lol this is all for headphones btw, I have nothing btw, I know all DACs plug into my wall but will my phone work as an audio source? also the coaxial is the 3.5mm jack on my phone to 3.5mm jack my DAC? ty guys so much!