the se535ltd-j sound great amped. they are sensative enough to run through a ipod/iphone. but imo the ipod or iphone doesnt have the kind of amplification qualities that a external portable amp does.
personally if ipod or iphone is a must go with a portable external amp/LOD combo. when i had my ltd-j i was running the ibasso p4 warbler with the lme49990 and a lod and believe me the sound quality was far beyond what a ipod or iphone can put out of its 3.5mm jack.
sometimes i feel like when people talk about the shures being sensative and dont need a amp. i feel like they are talking about how the iems can get loud without a amplifier to boost the volume.....while completely leaving out that if you get a high end amplifier its NOT just a volume booster. it improves the sound quality, with a lod you can get a cleaner signal, bypass the stock amplifier that imo are not up to the standards of ibasso,headstage,rsa or jds labs.
just becuase these are sensative doesnt mean that there are going to be benifits from amplifiers, personally i got no hiss with my p4 and the ltd-j. sound quality was AMAZING to say the least.
imo if you are rockin 500+ headphones and your running a ipod or iphone and you dont have a LOD or Amplifier you arent doing these iem justice. thats just my opinion