I'm looking into getting the Creative Soundblaster E1 amp for around $20. Would that be a good combo for my HD668B? I've read different things on the topic and most say that I wouldn't need an amp for these headphones. One reason is that its impedance is less than 80 ohms (56 ohms I believe). is Is that true? I might upgrade to the Audio Technica ATH-AG1x in the next two days so maybe I would need an amp for those? I might keep my Superlux but I'm not sure. Either way would the Creative Soundblaster E1 be a good buy?