HifiPal:
I am sorry, but there are some things that are missing from your explanation and there are some errors. I had explained this in detail somewhere else, but I am not able to locate the link. I will be brief.
There are four stages in converting a signal that is stored in a CD/DVD, a record, or a tape to music or sound that you hear on your speakers.
(Stage 1) The first is called the
source. This is a CD/DVD player, a turntable, a tape recorder, or the new MP3 players. Set aside the MP3 player for now. The other players read media of various types such as CD. DVD, Tape, and convert them to electrical signals. These electrical signals are very weak and are measured in milli volts. Some source players also perform Digital-to-Analog conversion of the sound signals.
(Stage 2) The next in stage is called a
pre-amplifier in the two channel world, and a pre-amplifier/processor or controller in the multichannel woirld. Let us just call them pre-amp for ease of use. What this does is to take the output from the source player and amplify it further to between 2 to 15 odd volts. A per-amp has separate inputs sockets for each kind of source such as Turntable, CD Player, Tape Recorder etc. It is important to connect the source players to only the specified sockets.
A pre-amp will generally have a single L&R output for each channel.
In the multi channel world, sound signals are stored with multiple coding techniques such as DTS, Dolby etc. Multi-channel pre-amps also have to execute the additional task of understanding these signals and decoding them to the proper channel.
(Stage 3) An
amplifier, or what is generally called a
power amplifier, takes the output from the pre-amp and further amplifies it to levels that can drive loudpeakers. This is measured in watts. Amplifier wattage can be anything say from 10 watts per channel to 100s of watts perchannel. An amplifier will generally have a single R&L input socket per channel and a pair of connections for each loudspeaker. A simple two channel amplifier, for example will have just two RCA sockets for input, and four connection points for the left and right speakers. The amplifier does not care what the source is and does not even recognise that. It just accepts the signal sent by the pre-amp and amplifies it for the loudspeakers.
(Stage 4) The final stage is your
loudspeaker that accepts singnals from the amplifier and plays your music or movie sound for you.
A
integrated amplifier is an unit that combines the task of a pre-amp and a power amp into one unit. The signals from the pre-amp to the power amplification are transferred internally without the need of any external connectors. Other than that the fiunctions are identical to a pre-amp and power amp.
Now take a 2 channel integrated amplifier and add radio receiving capabilities to it. You have a two channel
Receiver.
Now take a 6 channel integrated amplifier, add a radio to it and the capability to handle video signals - you have 5.1 Audio Video Receiver
(AVR).
Similarly take a 8 channel integarted amplifier, add a radio to it and the capability to handle video signals - you have a 7.1 Audio Video Receiver.
Please also read the following link:
http://www.hifivision.com/surround-amplifiers-receivers/1687-decoder-multichannel-amp.html
Separate multi channel pre-amps and power amps are very much alive and kicking.
Cheers