ATH-M50 Sound and Setup help

[Mrpico]

So guys I bought a recently ATH-M50 (Thanks for the recommendation) I couldn't use my PC because I was waiting for Windows 8.1 to arrive (Had problems for Windows 7) and when I plugged in my headphones it sounded just AMAZING! I couldn't believe how good they sounded, even on YouTube I could hear almost everything and sounded really good. The time I had used my ATH-M50 I used it with my PSVITA, my computer is an Alienware x51 (BEFORE YOU START BASHING ON ME let me tell you on why I have one. My dad knew the lead authority there (Don't if it was the manager, the president, the owner) who owe him some sort of deal so he hooked me up with an Alienware x51 i7 GTX 660, 8gb ram, 2tb for just $800, he also gave me a desk for my PC 

now I recently upgrade (Yes the x51 is upgrade able) to a GTX 760, i7 4770K and 16gb of ram. I don't think the Alienware x51 comes with a Sound card (I didn't see one either when I open it) 
 
So what I want to know is
1. Does the PSVITA sound really suck or does the onboard sound on my PC is significantly better than my PSVITA sound? (I don't necessarily think that the onboard sound is good) 
 
2. I was planning to buy a DAC/AMP and an Ipod Classic, Will this setup sound as good or better than my PC one? (I am planing to get a FiiO E18 or an E12) - Important
 
 
Also I forgot to mention most of my songs are 200-320 kbps 
 
Thanks for the help! And sorry if this post is a bit long 

 
 
Again thanks for the help and have a good day!