Can someone clear this up for me?

[snodog]

Seeing that I have always had a single av receiver I was looking into my crystal ball and seeing a bigger and better setup for my future (ahhh yesss) What I never understood was the amp and preamp combination. What is the common setup involving these? What is the advantage over a single reciever?

[Feanor]

Seeing that I have always had a single av receiver I was looking into my crystal ball and seeing a bigger and better setup for my future (ahhh yesss) What I never understood was the amp and preamp combination. What is the common setup involving these? What is the advantage over a single reciever?
A receiver is actually a tuner + pre-amplifier + power amplifier in one box. A receiver is a space and cost efficient combination. The major ecomomies come from a single chassis and, usually, a single power supply for two (stereo) or more channels. Note that an "integrated" amplifier combines the preamp and power amp but omits the tuner.

You can figure out what the tuner is. The power amplifier does principally only one thing: it takes a low current signal and makes it into a high current signal with enough power (amps) to drive your speakers.

The pre-amplifier, (or pre-processor in the A/V case), pretty much does everything else:

Lets you select your source - CD, DVD, tuner, etc.
Might provide phono pre-amp, that is, as stage that boosts the voltage from a phono cartridge into the range of other sources like the above, and corrects its frequency response.
Can direct the select source signal to a tape recorder or other, external processor
Controls the volume of from the select source: often reducing it, sometimes boosting it. This function mostly pertains to the voltage level (volts) rather than the current (amps).
Might control the left - right balance of the signals.
For A/V receivers, provides -- a whole lot of stuff -- in some cases analog to digital conversion; digital signal processing (DSP) perhaps including bass management, time delay, front-center-rear volume levels, and other effects; digital to analog conversion or PCM-to-PWM in the power amp is "digital".
Feeds the power amp with the processed signal.
You can have more than just a stereo preamp plus power amp. For example, the phono preamp (see above) can be a separate component, and the power amp instead of being one stereo or multi-channel amp, can be a single channel, i.e. mono, amp in which case you need two of them for stereo.

Why bother with separate components? One advantage is that the powers supplies are separate which, in principle, means better sound. Also, internal parts are more separated from each other and less likely to interfere electrically with each other. In practical terms, the high-end products are usually separates.

However maybe the biggest advantage is flexibilty, meaning a couple of things. First, you can upgrade on component or another without changing everything. This might cost you less money. Secondly, you might gain more choice in the way you connect your equipment. For example, you can put an active crossover between you preamp and powers amps which is the best way to bi-amp your speakers; (bi-amping is another subject). (I have this problem with my integrated amp: it won't let me put an crossover between its preamp and power sections in such a way that I can also drive a separate power amp).

Hope this helps more than confuses :)

[E-Stat]

Hope this helps more than confuses :)
Great description!

The only thing I might add is that some preamps or preamp stages in receivers may also include tone controls.

rw