Mp3s are affected the same as cd players are in the cold, its not so much the device as the batteries freezing. My solution is that I switch batteries on the way to the next stand, keeping one in my pocket to thaw out and one in the caller. The 9 volt in the amp isn't affected by the cold for some reason.
If you do decide to go wit an MP3 player make sure that you have the EQ set on natural, or vocal. Most of the little cheap mp3 players have the eq but is a bit hidden so read your owners manual.
Heres some pictures of my varmint al El cheapo. caller now has a lid clasp and padding on inside to keep stuff from banging around. Also painted in a tan camo.
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