Yes, i was so surprised when i received the Fiio E17 compared to my integrated soundcard, the difference is so huge, it's like i upgraded my cans to me, everything is so mych clear, impactfull, sharp, larger in soundstage, impressive how this little device can make the big difference.
598 with the E17 is good. But ther's another big jump in quality if you use a desktop amp like asgard. From there, asgard to higher level amp does not improve the 598 much more. But a proper desktop amp under $500 should give you a definite improvement over the fiio.