Well it will perform adequately from your phone or laptop, but resolution and volume will not be up to par with what these headphones truly can reproduce. I dont think youll need a 1000$ amp for these, that may have some benefits in the end, but the most bang for the buck youd probably get from a FiiO E11,E12 (+ FiiO D03K) or E18 or a JDS Labs 5C or Objective 2 Amp+Dac. I personally use an E12 + D03K, because i need Toslink and that combination workd perfectly well
Soundstage got bigger, detail got better, bass got more controll and the volume you can get out of this is deafening if you want it too, although id recommend using a maybe still loud, but at least reasonable level if you really want to have fun
Changing the cable will also give the bass a bit more controll, but the gain is only slight, but i mean for 5$-10$ you can get a tad better sound...^^
Personally use them all day everyday now, also have had the HD598,Denon D600,Sony MA900 the Astro A50s, but the Philips X1 was definitely the best for my taste. The Denon you should forget completely though, that really isnt a matter of preference anymore :O