I got the DragonFly 1.2 this morning. Tested it with 320k mp3 files. I A-B'd as well as I could with my laptop's soundcard
(Asus A93S with Realtek soundchip). Takes a couple of seconds to switch over though. I'm using 60€ Denon AH-D1001
My impression is:
Slightly more crisp, and therefore more punch, but this also lent itself to a slightly harsher tone in the upper-mids.
Slightly wider and rounder (front to back) soundstage.
A little less digital distortion in the lower end, and slightly more defined bass.
The main thing I wanted to get rid of was muddiness, but sometimes instruments still aren't quite as clear as they could be.
So it's not a huge difference.
I can notice little things if I'm listening for them, and A-B'ing, but my wife would probably think it was a waste of money.
Through the Realtek soundchip, my speakers, Panasonic and Sennheiser earbuds, and the Denon headphones all sound fairly similar to each other in tone and volume. However, through the DragonFly, they all have much more varied tone and volume. I hope this means that the soundchip is reaching its limitations, but the DragonFly has more to give. I think I need to try to borrow a much more expensive pair of headphones and speakers, and see if that makes a more pronounced difference. I don't actually know anyone with good gear though.
Also, the DragonFly is not powerful enough to drive my computer speakers (Philips SPA 2201) to their maximum output; they are considerably quieter than when driven by the onboard soundchip.
Further, when I plugged it into the usb 3.0 port that I wanted to use on the left side of my laptop, Windows gave an error about it not having some kind of ID, and that it doesn't know what type of device it is. The DragonFly doesn't display in 'Devices' at all, and I can't get the error to display again to make a note of it. It works fine in the usb 2.0 ports on the other side.
So as it stands, I would say that you always hope for a massive difference in these types of purchases, but in the end it's actually kind of disappointing.