I just got a dragonfly, and I'm very impressed with the sound. When I first started using it on my laptop, it worked great when the pc was plugged into the AC. However, as soon as I unplugged it from the wall I would get pops and static and zzzzztttt sounds. There was no way to make an improvement using the power management options for USB in the device manager.
I solved it by plugging the dragonfly into the port on the left side of the pc. I have no idea why this worked, but I'm glad it did. I'm using a Lenovo ideapad p400 with windows 8 by the way.