It's clear these manufacturers design their motors to sound good and the buyers expect them to sound like they sound. But mechanically, how do they manage to have such a distinct sound? Could other smaller motors have an equally pleasant sound?
A lot of the European cars use what's called a flat-plane crank as opposed to a crossplane crank as seen in most American V8's. There are a few exceptions, like Ford running a cross-plane crank in some of the Mustangs. The flat-plane is so called because all of the rod journals are on the same plane with each other, where a crossplane crank has four throws at 90° to each other. The flat-plane crank configuration, along with a different firing order, as well as exhaust differences, create the different sound then what you're used to.
If by "smaller" you mean a 4-cylinder, no. The note comes about because it has more cylinders to fire per revolution of the crankshaft. A 4-cylinder is already a flat-plane crank, as all of its throws are on the same plane.