I just purchased a pair of audiophile Sennheiser HD 650s online because my HD 555's are getting old and breaking down. I have a policy of upgrading technology every time the old stuff wears out, so I got the twice-as-expensive headphones this time around (and I'm excited for them to get here). But I have some questions...reviews and how-to guides online are saying that for audiophile headphones you really need a DAC amp to get the most out of them (such as the FiiO E9 Desktop Headphone Amplifier and Dock for E7 USB DAC since I'll be using it for my desktop computer), but I already have an X-fi Fatal1ty sound card in my computer. Do I need to buy the DAC amp, or will the X-fi Fatal1ty be sufficient? Should I just throw out the X-fi card and plug the DAC into the motherboard?