That's something I wish I had the answer to, because I've been eyeing the DT880 Pro for awhile. The DT880 is more to my liking for music than the Q701, but the reverse is true for gaming. Still, I feel that they are close in quality for music, but the Q701 definitely wins for gaming. In any case, the Beyers don't have the deepest cups, so your ears will touch the padding in front of the drivers. I don't find that uncomfortable one bit, whereas the AD700s relatively naked drivers shocked me once in a while. Going from the AD700 to the Q701 would be a very clear upgrade, as I feel it is the truest upgrade to the AD700.
In other news:
So I've been A/B-ing the NFB5 with the E9 (both running off the NFB5's DAC obviously), and it's literally too close too call for the D7000. I'm damn certain that at the same decibel level, I would fail blind A/B tests everytime. So even though the E9 has a high output impedance, which isn't ideal for the Denons, i honestly can't hear anything impacting performance. It's just good music with either amp.
The Q701 sounds just slightly more fluid off the NFB5, where it sounds a little dryer off the E9, but the difference is small.
Again, the output impedance of the E9 should be negative affecting both headphones in comparison to the low impedance of the NFB5, yet it sounds too close too call.
I'm not one of those to fall for new toy syndrome. If I hear CLEAR differences, I'd say it. I'm not. They are both great sounding amps.
If anything is different is that the drier tone of the E9 makes it more analytical, where the NFB5 is more musical, just slightly so.
So all in all, I'd say the NFB5 is for those that want clearly more power than the E9 for some hard to drive cans, but that the differences aren't gonna be jarring for headphones that they both can handle well.
Of course, people here on Head-fi always go for the more expensive stuff and always say it's better than their older equipment, but I wouldn't BS you guys with that hyperbole. If you have an E9, be happy. It sounds great. As far as SS amps go, I doubt you'll find something to REALLY blow it away in comparison in the logically affordable price range. I'd just look for something with a clear coloring of sound if you want different, like a tube amp.
edit: I might have to rethink what I said about the Q701s.... they might actually be better for me now over both the DT880s AND 990s. Just something about them that is just damn awesome.
There is no glaring flaw with them. Seriously, they're just good. Where the DT990s get a bit screechy in the treble, the Q701 just sings happily. The bass AND mids are pretty damn good, as well. The only drawback being sub bass isn't as emphasized as what I'm used to, yet it's not something that can offend the ears like the DT990's treble. The Q701 sounds so rich, and musical. Just not what I expected. AT ALL.
