So I've tried the E17 + E09K combo vs. Hot Audio DAC Extasy + E09K and I definately prefer the latter. The E17 is a solid all-in-one unit especially for the price, but I don't like the DAC portion. The E17 is a solid budget stepping stone but if you can, definitely upgrade. I've got an O2 amp incoming as well as a Sense G5 amp coming from China. I'll keep the amp that works for me and sell off the others.The HE-400's are so good, so so good!