...thats over $100 for me

I was initially gonna go for the a900's but i thought it was stretching out my budget a bit. As you can tell, im pretty new to the headfi thing so my apologies.
Anyways i do have some questions before i make the purchase:
-Will the phones sound fine enough without an amp (my power source will be coming from a Zen V Plus but i might get a Cowon D2 somewhere in the future)?
-Ive demo'ed a HD 595 unamped and was wondering how the a700's sound would compare.
-ive been hearing that the ath series are pretty big so i was wondering how big it looks compared to said 595's
Again im sorta new here so please be easy on me?
Thanks