Improvement in sound if i leave my CD Player on.

let's think about this logically, we are talking about a component reaching thermal stability, warming up. So the easy way to tell if there is a hope in hell of the sound chnaging over a certain time period is to turn the damn thing off, let it cool, wire it up with ashit load of thermocouples and take readings every ten minutes or so.

If they level off after 30 minutes and do not chnage thereafter, then guess what, you are hearing things. There has to be a thermal difference to be an electrical difference, you just have to measure in the rigth places.

i'd warrant any none valve cd player with sufficient cooling ventilation will be at max temp all round after an hour or so, unless the caseworks heatsinks components.