I have a pair of Sennheiser MX880 which I use at work. I do find the sound quality somewhat lacking, compared to my Beyer DT880's, so I was considering upgrading to a pair of MX980 (thread about that here: http://www.head-fi.org/t/614512/why-do-small-headphones-sound-bad#post_8469241)
But would a amplifier like the Fiio-E10 improve sound quality from the MX980's significantly at low volume? From what I can read, the MX980 is an improvement over the MX880, but probably not a HUGE improvement, so I might not find the difference to be night and day (which is really what I'm looking for)
I tried a Audio-GD NFB12 with the Beyers on my laptop once, but was honestly not able to tell any difference, even though they are 600 ohms and should benefit from the amplification.
My laptop suffers from noise on the headphone output, so I would dampen the MX980's with the volume knob.