Great details and the soft light really helped. There is a tiny dust spot in the upper left. Did you lighten the eye? I'm wondering if the black of the eye looks a bit washed out or if it is due to the reflection.
I wish I had a local pond this these guys in them. Nice work on the tight portrait. I might try desaturate the red at the eye and/or eye ring. Also toning down the white on the beak. I now these guys are tough to expose due to the extreme contrast they have in the plummage, beak and eye.
Axel, the eye looks the way it does because the duck was standing on snow covered ice which was reflecting into the bottom half of the eye only making it whiter/lighter than the top half.
I did some selective darkening to even out the eye reflection a bit better.
Also took Robert's suggestions of desaturating the eye ring a bit and toning down the bill even more than I had originally.
Stunning image and lovely repost. Love the excellent color and detail as well as the crop you chose for this image. Killer BG too. Thanks for sharing Mike.