Just for looks?

Size does not matter. A handful is still a handfull.....

oops.

I am inclined to think that it is how any given amp-regardless of design or appearence, matches with the speaker of your choice. Certain aspects of a amplifier may seem preferable on paper or by appearance, but the real telling is when you hear the results of that amplifier with your speaker.

Amplifiers with large caps and transformers are generally designed to deliver more current to a power hungry, high wattage output stage but this alone does not equate to good sound quality. However there are certain applications that require this high power, high current, like power hungry speakers. Many audiophiles feel that amps rated more than 100 watts per channel loses the sweet spot. The main reason for this is because higher wattage amps require more electronics and output devices. The more electronics a signal passes through the poorer the sound quality. A case in point is most audiophiles prefer the sound of the lower powered McCormack DNA 0.5 (100 watts per channel) over the higher powered DNA-1 (185 watts per channel). The ideal strategy for any engineer in designing an expensive high end amp is to keep the signal path as short as possible and use the highest quality parts, this is why a small high end amp can be so expensive, your paying for engineering, design, & parts quality.