I would definitely pick the HD598. The Momentum is a great closed portable headphone for music, the HD598 is a great open headphone for detail whoring (The open design = better soundstage, better soundstage = better positional cues). I'm sorry to rag on 7.1 headsets because they were a neat idea, but TB pioneered them and other peripheral makers fell into line, they all suffered the same problem: they could never beat out traditional headphones with bigger, more sophisticated drivers.
i was browsing on headphones and amp's , i found the Fiio E17 device that enhance the sound for headphones , do you recommend the HD598 along with the Fiio E17 amp together ? as for epic quality sound , what do u think
Fiio is a great company and their amps are really good. The E17 is a great little device that has served one of my audiophile friends for many a year, but if you don't want to bring it outside then the E09K is the one I would recommend. I don't personally own the E17, but I have it on good authority that it is just slightly worse when it comes to powering headphones then the E09K, but the E17 is portable. Your call.