Music just won't play loud enough on Samsung Galaxy S4 i9500 On my Macbook Pro, iTunes lets me take advantage of my Sennheiser HD 380 headphones. I can lift the sound as loud as I like. 

On my Samsung Galaxy S4 i9500, I just can't get near as loud a response from my headphones. It's very quiet. 

(How can my computer's operating system give me far greater feedback than the Android operating system on my phone?)

Please advise how I can achieve the same sound quality with the Android OS.

Thank you.
This might actually not be a problem caused by the operating system but rather by how much voltage the device can output into the headphones.
So, your Macbook is more likely to have a more powerful audio output than your S4.
The key word here is impedance. I assume the headphones you mentioned have a impedance too high for mobile devices, such as the S4.