Hi Brrgrr,
You may have seen my review comments
HERE (Post #65) about the Magtech running cool.
The Magtech runs cool because its transistors have an extremely linear transconductance function and therefore do not require much bias to eliminate crossover distortion. Understand that most of the heat produced in a Class AB amp is produced by the bias current. The sole purpose of the bias current is to eliminate distortion. Through the use of the most modern and linear Thermal Trak transistors very little bias current is needed to eliminate all distortion and the amplifier as a result runs very cool. Impressively, the Magtech idles with each channel drawing only about 16 watts of power, so the total idle power used by the amp will be about 32 watts.
The inch deep heat sinks along both sides of the chassis, which look oddly insufficient for the amplifiers power rating, mercifully lack sharp edges and are child safe but closer inspection of the heat sinks however reveals there are no less than 53 fins, each with a surface area of 10 square inches. When you add up all this area, plus the area of the aluminium chassis, which also dissipates heat, the total heat sink area in the Magtech amplifier is nearly 10 square feet! As a result, the heat sinks are adequately designed to keep the amp cool.
That said, exactly how cool the amp runs will of course be a function of the load and the ambient temperate of the room. I used mine in an air-conditioned room and in that situation if the room is cooler than the amplifier, the amplifier will be barely warm to touch.