I've always been pretty skeptical of headphone amps and expensive supplemental audio equipment in general. My Macbook Air had always driven all of my previous cans to my satisfaction. But today, for the first time, I tried using my DT880 Premium 250OHM cans with my mid-range Denon receiver so I wouldn't wake up the roommates with my speakers late at night. I was absolutely floored by the difference in energy and sound quality. I'd say there was at least a 50% improvement in the midrange ene, an area where I had felt the cans had been lacking in due to their clinical sound signature. The bass was also punchier— louder, but not any dirtier. They sounded like different headphones— taking everything I enjoyed about my old B&W P5's energetic signature, but keeping the many advantages of the DT770 (more accurate highs, much wider soundstage, and the physical comfort on my ears). I spent 30 minutes switching between the receiver and my laptop, playing my favorite songs, and I was just shocked at the difference. I wasn't even TRYING to discern little details. The difference was simply obvious to even the least experienced double-blind listener, I'd suspect.
Tomorrow I'm purchasing a portable headphone amp that I can take with me (I commute a lot, and believe it or not, my BD carrying case fits perfectly inside my messenger bag with my laptop and work docs).
I probably won't spend more than $100, but I feel like even a cheap Fiio amp will make a big difference. Not specifically asking for recommendations, as this isn't the correct forum for that apparently, but just wanted to share my thoughts to any doubters of headphone amps on those big cans! But you can post recs if you want to :)