There clearly are measurable differences between cold and warm electronics, and it's of course a fundamental physical principle that as the temperature increases the conductivity goes down in conductors and up in semiconductors.

However, there are clearly measurable differences between cables too.  I suppose it's conceivable that the difference is sometimes audible in some kit, but I can't honestly say I've ever noticed it. The whole warm-up phenomenon is an obvious candidate for the power of placebo (how come cold electronics are never reported to give a 'warm' sound?)