thats not surprising. my DR100 mkiii outperforms both the zoom f6 and mixpre6 in distortion in my measurements. These prosumer multichannel units all seem to be a compromise to squeeze all the features and channels in
I have a DR-100 too and i love it, but only use digi-in. So the analog in sounds great too, good to know.
I was all set to buy one of these, and then the F6 came out and its 32-bit float recording swayed me in that direction.
If I needed something more compact and was shopping today, I would seriously consider the DR100. Those AKM DACs are supposed to be excellent.