[Argus25]

Maybe its because I live in Australia and the ambient temperature can hit 40 Deg C, or maybe its just a plain silly idea to try to squeeze powers like 2 watts out of an IC (or transistors) in an epoxy package without a proper heat flag.

Power output transistors , at least TO-5 and T0-220 etc, the transistor die is thermally bonded to the metal case/flag. That way the thermal resistance is much lower. To expect a great result trying to extract heat via IC pins from small junctions in the IC body to me is a somewhat optimistic bodge, especially considering the geometry and cross sectional area of the pins.

Sure, you can get it to work, but I would never label it elegant, the junction temperatures of the output devices in the IC will run in the high range and depending on your ambient temp, it can push them very hard. It all equates to a shorter life for the IC.

It became the fashion for example that the vertical scan amplifier stages were built into one IC in many latter day video monitors. These amplifiers are very much like their audio amp counterparts. Seemed like a good idea for the manufacturers, but as the years have past these IC's are dropping off like flies.

The situation can be a little improved if the IC is a type with a metal top where you can thermally bond it to a good heat sink.

My advice for an amp over a couple of watts, get one with an IC with an integral heat flag that you can screw to a decent heat sink, of make it out of discrete components, with output transistors you can screw to a heat sink.