Thermal Distortion your loudspeaker most likely suffers from it. But do you care?

Thermal distortion from my speakers. My ears would blow first! :)

I would not claim to be an expert on thermal dissipation through a conductor which travels through a magnetic field.  However through the  decades of experience in electronics and and a hobbyist at speaker building I do know that the speakers that I used have a  vented pole  piece which aids in keeping the speaker cool while in operation. Also it has a large magnet which helps, large compliance, spider to aid control. Most quality high excursion woofers use this design for that very reason. There is much science applied when figuring the "thermal factor "  My woofers came with technical blue prints showing Q, free air resonance, magnet weight, cone mass , pole gap magnet strength. and so on. So what?  As back EMF is created by a speaker conductor going through large excursions  the thermal distortion is minimal compared to other factors.  One of which and foremost the power amplifiers ability to deal with back EMF which is the reverse movement of the cone throughout music reproduction. I tested several high quality, high current,  solid state amplifiers that could not deal with it and distorted before the speakers did. In my case the best bang for the buck was a quality tube unit. The cones move more, no distortion. That was one of many examples. Matching the type of speakers with the best amplifier makes a huge difference. Also, if you exceed the rated RMS continuous rating to get great dynamics, then you are mismatched. This factor remains true with tweeters and mid range drivers as well.  Most important is the end result, sound. My comments are strictly for completely passive speakers. Thermal problems causing audible distortion is the least factor to be concerned with.