Cold Weather Sleeping Pad

[bigsky2]

I currently have a Big Agnes Air Core. I did a backpack hunt in AZ in December where it was getting down into the 20's at night and I froze my butt off so I am looking at getting a new pad for colder weather. My friend I was hunting with had the Therma Rest Xtherm and he was comfortable. We both have 15 degree bags. Aside from the Xtherm, does anyone have any suggestions for a pad that would work well?

 

[Clovis]

Exped Downmat 7 has worked for me in similar circumstances.