[Matthew Zepess]

I just decided to splurge on a pair of Sennheiser HD 558, I heard that its not neccessary to have a amp, But is something you should look into. Ive always heard alot of great things about FiiO Amps Whats the difference between something like a e6 vs a3 and so on... im also guessing the e10k needs a constant power source? I would probably like a portable one, Hopefully something that can be plugged into a constant power source when on a laptop but also have its own battery when traveling.