Amplifiers: High Current? High Voltage?

They don`t control current. They should dump it into the load when needed. All amps can`t do this.

Then what is the best way to describe a non current restricted amp from a current restriced amp? High current vs. low current? I assume a non-current restricted amp is one that will put out nearly twice the power at 4 ohms than at 8 ohms.

Ballsy amps, as far as current delivery is concerned, double down (they deliver 2x the current into 4 ohms that they deliver into 8 ohms & 4x the current into 2 ohms). For example 300W into 8 ohms, 600W into 4 ohms & 1200W into 2 ohms.

First, I don't know that "controlling" is the best word to use in this situation. Many, Many high quality amplifiers use little to zero feedback, espcially in the current gain sections.

A better understanding may be had by thinking about the speaker itself. A voice-coil (or any electro-magnetic mechanical device) is driven by changes in the magenetic field. Electro-magnetics have a direct relationship with current, not voltage. In a voice-coil, the only reason to have high voltage is to overcome secondary effects, such as "back-emf" (an electric motor terms, but it applies here too).

Many amplifiers are designed in the voltage domain, from the perspective of wave form replication, and have devices (tubes, transistors) that are capable of high current. This is valid because of Ohm's Law or V=IR. The resistance is set by the speaker coils, and the current in then a fucntion of the voltage output.

This does not apply for electro-stats, as the rely on HIGH voltages to create the static field.