why amp heats up?
1. amp is working at full potential.
2. amp's heat dissipation is good.
3. amp is running at low impedance.
4. amp having prob with grounding
5. amp is overloading
for 1 and 2, it's good...
but for 3, it will shorten the life of the amp..
for 4, it will decrease the performance and spoilt eh amp, unexpected sound may produced..
for 5, it definitely gonna spoil the amp, but most amp got protection for it..
why amp doesn't heat up?
1. heatsink design doesn't match with the power amplifier heat dissipation rating..
2. amp is running at higher ohm, low current and low performance.
3. there's cooling equipment.
4. amp not working

whahaa
a amp that doesn't heats up is not good....car amplifier casing design is to dissipate the heat from inside to the outside. if ur amp doesn't work that way, u might have a short life amp..