Hi everyone a year and a half ago I got my first new pair of headphones (Phillips Fidelio X2's) and love them however the sound has always been on the low side of things and I also want to get a bit more out of them with a amp/dac. I have little to no knowledge on amp's/dac's. What do you...

Hi everyone,   I currently have Sennheiser HD558 and had them for a while I'm looking for an upgrade.   I listen to rap,hip hop.   Looking to spend $750 if there is a significant upgrade for a little more $$ then i'm interested and open for suggestions.   These headphones will only be...