sound card for headphones

[arijit4885]

I guess there's a serious problem when my recently bought headphones senn hd 215 sounds better with my sony w700i mobile than with my pc(onboard sound realtek).So could someone suggest to me a decent midrange sound card thats not too pricey?
also, what is a headphone amp and is it necessary for listening music on the pc?

my budget for sound card is 1000-2000 bucks

 

[desiibond]

Get Creative Live! 24-bit (PCI sound card). I think it costs around 1.5k