Selecting the right prosumer-grade espresso machine for you can sometimes be a bit of a challenge. With so much gleaming stainless steel and commercial-class components, how do you determine which model is worth your investment? Take the Livia G4 and Giotto Evoluzione, for example: These are two heat exchange espresso machines, which allow you to brew and steam at the same time, that have polished stainless steel cases and are designed to work on the 15 amp, 110 power circuits most often found in home kitchens. Feature-wise, the Livia G4 comes in a few different configurations -- a traditional semi-automatic, a semi-automatic with a PID and an automatic with a PID. The two models that incorporate a PID enable you to control the steam boiler's temperature, which will in turn affect the water in the heat exchange that is delivered to the brew head. Pasquini designed it to also incorporate a thermoblock at the brew head, producing a consistent brew temperature while not requiring an upgrade in the machine's power requirements. The Giotto Evoluzione, on the other hand, is simple yet refined: A traditional semi-automatic with an E61 brew-head and the ability to either use the internal water reservoir or plumb it in to your home's water supply. While it doesn't have any programming options, the brew head design and heat exchange technology produce a consistent brew temperature, backed by a very hearty steam boiler. Watch as Teri guides us through a detailed overview of the features and specs of each machine, then demonstrates how they compare, performance-wise.