iPhone 5S sounds low when using earPods

Hello,

I own iPhone 5S, iPOD classic 160GB 7gen...
...
My iPhone 5S speakers are louder (as expected) but...
when i listen using earPods, iPhone is much lower in sound..

..
Test made....
..
Same song...
loud, crisp and clear on iPOD classic
low sound and high bass on iPhone 5S.

Is this normal ?
Should i visit apple store ?