Professor:  The single most important thing you can do to extend the life of electronic products is to keep them cool. For every 10^oC (18^oF) hotter that equipment runs, the life of the components is cut in half. Since we have eliminated the need for a fan by using massive external heatsinks and many internal heatsinks, it is absolutely crucial that there be adequate air flow around the amplifier.         Do not place the amplifier in an enclosed cabinet.