It is worth pointing out that not all class D amplifiers run necessarily as cool as cukes...
There is in my opinion the possibility that as design elaboration of amplifiers based on new generation class D technology increases, some future -- and totally hypothetical implementations -- from any number of manufacturers -- may potentially generate fair amounts of heat, and therefore benefit from hefty chassis, fins or other heat dissipation mechanisms.
Even in retrospective, we can find examples of heat generaating class D amplifiers. For example, the withdrawn Rowland Continuum 500 integrated, a 44 Lbs midrange class D design based on the ICEpower 1000ASP module, generates a considerable amount of heat, and runs quite toasty to the touch.... And no, the device has regretably no cooling fins.
In this particular case, I conjecture that two circuit elements in C500 may be major contributors to heat generation... a bunch of bulk output capacitors, and a 1500W PFC-based current rectifier.
As usual, only time will tell what the future brings... Oops, I suspect I just spewed out a repetitively redundant tautology... I meant... Oh well, never mind *sigh!*
G.