Quiet cooling fans for audiogear

a Variac can be used to reduce AC input voltage & slow down most muffin fans to acceptable low-noise levels.
Be sure to draw heat away from the component - don't blow cold air onto it.

Bob the reasoning is so as to not introduce thermal stress points due to larger temperature differentials across a small heat-sinked area. Cold air blowing directly onto component causes a much larger thermal stress differential over a smaller area, with corresponding variations in semiconductor operating temperature, vs. drawing the colder air across a larger thermal area via drawing heat away from the heat sinked area.
Similar issues are noted when using glassware; thermal stresses occur across an even smaller glass area of a tube envelope vs. drawing the heat away.

no - the cooler air is simply spread out over a larger area