Well Mani , I am using the 598 SE since about 2 years. Its a very nice open back headphone and was decently priced when i bought mine. Having always used closed headphones my entry to open backs was first with the Sennheiser HD 437 which itself was a decent headphone. After a period of time my wife started enjoying these and I had to look for another and ended up with the 598SE. Being 50 Ohm it can be driven with normal ipods/mobiles but to extract the best performance you need to use a dedicated headphone amp. Even a simple Fiio M3K will make it shine.
It give a flat balanced performance but is not bass heavy. Please reconsider if you want thumping booming bass. I use it with my Fiio M11 or my Ipad and am quite happy with it.