I ordered a pair of Audio Technica ATH-AD700 headphones and I will be using them with my iMac. I was wondering if I needed an amp or external DAC to use it to its full potential, or if the sound card already inside was good enough. This is my first set of good "cans" so I'm not an audiophile (yet...). Keep in mind that I also play FPS's quite often so I think Dolby Headphone would be a big plus. I'm new to audio, so tell me what you think. Thanks.