Well, I wouldn't say it would be a good idea to come out on a -10F morning (gets that around here, UGHHH, give me heat over cold), turn on your car and turn the subs all the way up.... Let them warm up a little but before getting too loud.
You know what you guys need? Couple of Sony amps in your car. No heater required. Those suckers run hot even with no load. Have one near the driver's side and it'll keep your feet warm.
Yea, see, run your Sony amp/sub combination when you start the car up, and feel free to blast it without warming up. This way, you good sub/amp will warm up while those pieces of garbage work away. Either way, you won't lose much money, and still get your bang on the way to work/school.
Its ok to run electronics in the cold, thats what they like. LCD displays might be kinda slow bc they dont like it that cold. As far as the speakers go however, or anything mechanical for that matter, is gunna have to be warmed up a bit before you blast it.
Find it kind of funny though. My vintage home gear...it takes a beating in the summer. My house doesn't have A/C, so you can imagine how hot it gets in the summer when I'm playing music at high levels. And I don't use a fan on it or ANYTHING, and never gotten an ounce of trouble from any of it.
Gotta love the build quality of gear from days gone by...