I mainly listen to pop and rock (majority pop), I've been searching around and heard about these:   HD 598 HD 600 HD 650 Fidelio X2   Which of these should I go with? I'm also open to more suggestions, my budget is $700.

I'm kinda new to all this. You can mount the Fiio E17 to the Fiio E09K, but what does that do? What's the difference between the E09K and the E17?

I'm considering buying the DT 770 250 ohm's. What would be a good amp to drive them?   I was thinking of the Fiio E10, but it's out of stock everywhere in Netherlands. Is there any other amp by Fiio that works like the E10? I really prefer a desktop one rather than a portable one.

I don't know much about amps, and I'm pretty new to all this. I was thinking of buying the Beyerdynamic DT 770, but I've read a lot of posts on this forum saying that it needs an amp. I'm planning to use those headphones on my PC and nothing else. Amps can be used with PC's.. right? Would the...