Based on your own testing, I think it would be safe to say they are affected by the cold. The other post about the cold effecting your own hearing could also be part of the equation.
While I think it would be interesting to have a controlled test of this done by the manufacturer, I would not expect them to have this type of environment readily available.
Although, maybe Ian could open all the windows in his house in the dead of the Canadian winter.......nah, Amie would never go for that!
Can you turn on the system, and let it play for an hour to warm up and then go back and listen?
