if i wanted a 5.1 setup(for the audio only), i could just use an integrated amp?
Let's get back to basics first.
Amplifiers have 2 sections: the pre-amp (where you contol inputs, volume, and where signals from your source is prepared for feeding into the 2nd section, the the power amp. If these two sections are in separate chassis, then you have separates.
If the 2 sections are in 1 chassis, then you have an integrated.
A reciever is an integrated amplifier with a built-in tuner in the same chassis. A receiver can be 2 channel (e.g., NAD 7-series stuff).
An HT receiver is called so because it has amplifier, pre-amplifier (where the Dolby Digital/DTS/etc. decoding happens, a.k.a. the processor and hence the term pre-pro for separate HT components) and in most cases, an FM tuner also.
The difference between a stereo receiver and an HT receiver is the former has 2 channels of pre-amp and amplification only, the latter at least 5.
I am assuming that by your question, you mean this: "can you just get an integrated STEREO amp for use with the pre and power amp sections in your stereo mini-compo to power a 5.1 system?"
The answer is no.
First, you won't have a 5.1 decoder in whichever you decide to use as pre-amp, processor.
Second, you need at least 5 channels of amplification for 5.1 and your stereo mini-compo would have 2 plus only 2 more on the integrated.
Third, having different amps driving different channels is more likely to give you an incoherent surround soundstage than using the same amps across all channels.
i already got a mini-component so i'll just use its tuner. or are there receivers w/o the tuner and video switching capabilities? i only wanted the audio to be 5.1...
Check first if your mini-compo has an audio out if you like to use it as a tuner. Most mini-compos don't have this.
A receiver without a tuner isn't a receiver anymore.
If you think by taking out the tuner and video switching on an HT receiver will allow manufacturers to come out with cheaper products, think again. Taking out tuners and video switching will only save manufacturers a cent or two as these are really cheap silicon chips manufactured by the millions.
Why do you want 5.1 for audio?
Have you heard a straight stereo system compared to a 5.1 system? At the same price range (and assuming competent set-up and matching), chances are the straight stereo system would trounce the 5.1 system on stereo material.
Chances are, you'd only want 5.1 for audio if you have a hi resolution multi-channel source (SACD or arguably, even DVD-Audio) as well as a large enough selection of multichannel music software. In my almost a decade in the hobby, I have yet to meet a music lover with more multi-channel material than stereo albums.
oh, by the way, which is more expensive, the A/V receivers or the integrated amps?
If you're buying new, entry level Rotel stereo integrated, you'd spend sub PhP15k w/c is about what you'll spend for an entry level Yamaha or Onkyo HT receiver. So in terms of cash outlay, they are within ~15% of each other.
However, if you divide the cash outlay by the number of channels, your cost per channel is higher on the stereo integrated. And most specially at the entry level or budget range of good gear, you do get what you pay for.
Bottomline, you need to decide what you are out to achieve.
If you listen to lots of multi-channel material and you like effects steering, go 5.1.
If you like simple, good old stereo, it can be pretty amazing what a 2.0 sytem can achieve.
