My mid-range and tweeters have ferrofluid. I suspect that warm or hot ferrofluid behaves differently than cold ferrofluid. Also hot speaker coils have higher resistance. For copper it would be 4% for every 10degC. Drop in power is negligible, but increase in resistance might affect crossover points.
Do speakers take time to warm up?
For example, if my stereo is on and has been on for weeks, and then I connect speakers that have been sitting idle for a few weeks, do the speakers sound better after an hour of being played? Whats going on? Is it the caps in the crossover, the drivers, the ferrofluid in the tweeters? All of the above?