Receivers, Pre-amplifiers, Power amplifiers, Integrated amplifiers
What is what, and basic familiarity with the aforementioned.
Source Devices:
Source devices are components that handle the playback of your content and material. They are responsible for all aspects of controlling playback - pause, play, fast-forward, rewind, etc.
If these devices are using analog outputs, they are usually outputting consumer line level (~316mVRMS for consumer equipment).
If they using a digital output ( optical, coax, HDMI, etc.), the audio has not yet been converted to analog (AC voltage), so you don't need to know this.
Examples of source devices are blu-ray players, CD players, cable boxes, etc.
Pre-amplifiers:
A pre-amps most basic job is to provide a volume control and to have the ability to take a line level signal, from a source device such as a CD player, and provide enough gain to feed a power amplifier.
Consumer power amplifiers generally require much more voltage than line level to reach maximum power output. This could be any where from 1-2 volts, and sometimes but rarely more. This specification is listed as input sensitivity. The pre-amplifier has to ensure it can take the low level signal from the source device and boost the signal up to meet the power amplifier's input sensitivity specification.
Not only does the pre-amp provide volume control and potentially a significant amount of gain (depending upon where you set the volume), but in more complex and most real world systems it is the device that offers a significant amount of the features you want in your system. For example, input switching between source devices.
For example, if you want the capability to run a system in another room, room correction, HDMI switching, digital to analog converters, etc. then make sure your pre-amplifier offers it. Beyond just its basic job of being a gain stage and volume control, think of the pre-amplifier as the hub, or brain, of the system. The pre-amplifiers that have digital signal processing (DSP) will commonly be referred to as pre-amp/processors.
Power Amplifiers:
A power amplifier is responsible for taking AC voltage and amplifying it. It takes much more than line level to push your speaker drivers in and out enough to move air molecules with enough pressure to make loud, clear sound. A power amplifier is responsible for taking small level AC voltage from a pre-amplifier and providing enough gain to power your speaker's drivers.
Receivers:
A receiver is a pre-amplifier, AM or FM tuner, and a power amplifier built into one chassis.
Integrated Amplifiers:
An integrated amplifier is a pre-amplifier and a power amplifier built into one chassis (the difference between an integrated amplifier and a receiver is that the receiver has a built in tuner).
Integrated Amplifiers:
An integrated amplifier is a pre-amplifier and a power amplifier built into one chassis (the difference between an integrated amplifier and a receiver is that the receiver has a built in tuner).