Thanks for the reply. I'm not so worried about volume as I am having a good frequency response across the whole range. My guess is that amps not designed for driving lower-impedance headphones will roll off on the bassy end. The headphones in this case are Sennheiser HD580 Pro's, though I'm curious about how low a 'phones impedance can go and still be driven well by the E17 in general.
I don't think you would have any problem honestly. That's something that depends more on how difficult are the headphones to be driven. The E17 drives perfectly all the AKG K7xx and Q701 series and they are known to be pretty difficult to drive. Same range of impedances. You are good to go man.
EDIT: if you are specifically concerned about the bass, you might wanna check the E18 as well, that IMHO behaves better than the E17 in the lower frequency end.
Edited by Ashade - 12/28/13 at 12:45pm