Does it make sense to look at portable amps cause most of the time i will use it on the go. Thx again
Can't help you much with portable amps as I don't have any and only tried a few. Also, I don't use my TH-600 while I'm out, I usually use efficient headphones like Momentum Over-Ear, MDR-1A or Vmoda XS so the Fiio X1, X3 and X3ii are more than enough. As for portable amps I really don't want to carry around anything extra, a lot of times I'll just use my Galaxy S5 with the Vmoda XS as even the Fiio DAPs are too much to lug around. Since you have an X5ii then you might want to look at a Fiio amp, they make holders that will pair the DAP and AMP together so it will be easier to manage.
Good Luck