how often i can bump my thread? :) also what, nobody can't help me with this or i'm about to ask something impossible?

greetings everyone i want to upgrade from my fiio e10 to something REALLY BETTER and have near 300$ also can buy a used one dac my headphones are Sennheiser 600 hd and i also listening all kind of music, so it would be great if the dac will be neutral and can handle speed-metal genres if...