Home Cinema amplifiers come in all shapes and sizes. Integrated amplifiers occupy the largest sector. When considering what your after just follow a few rules and avoid many of the myths.
DSP.
Don't become over concerned with DSP effects. Munster Cathedral effect may all be very well when you first buy your amp, but the likelihood of you ever using it for sound reproduction is pretty slim. Worse still, having 60 completely user definable DSP (Digital Surround Processing) modes means that the quality of the things you do want have been watered down to pay for these gimmicky extras. A few DSP effects can be handy for the playback of old movies or for when you listen to old programs off of TV to give you a bigger sound. But some companies overwhelm you with ones you just cannot even conceive of a use for. We have even seen 'cave effect'!
It's also interesting to note that decoding chips, like computer chips, come in lots of different qualities. Some manufacturers use DAC's (digital to analogue convertors) and Decoding chips of far lesser quality, this keeps the price low, but also the sound quality.
Power.
Wattage is perhaps the most over-represented thing of all. Most amplifiers will offer you huge outputs - 100 or even 150 watts. So what does this realistically mean? The answer is not a lot. Most Japanese amplifiers give massive outputs when measured into a computer on the design table, however when used into real world speakers, realistically, they run out of puff. This is because they don't have the current to back up the wattage.
We've all had a cheap and cheerful amp at some stage, and you have no doubt noticed that by the time you get to about a third of the way round the volume the sound starts to distort and become busy. This is a lack of drive.
Much better to have an amplifier that is designed to give you a lower wattage but with much higher current delivery. This will look bad on the advert, but in realism it will give you an amplifier that will quite happily produce good, undistorted sound, right up to the end of the volume travel. Rather than one that gives up at just a third.
Imagine you take eight treble 'A' batteries and wire them together. This will give you 12 volts - however if you try to start your car with it, it's not going to happen. This is because they simply wouldn't have the current.
Up-scaling
Many amplifiers are coming with built in scalers. What's that? A scaler can accept composite, s-video and component signals and then send them all out of one component or even one HDMI connector making connection to your Plasma/LCD/Projector much simpler.
So we must all have that then. No. Expecting your amplifier to scale up your pictures like a separate scaler could do is unrealistic. A good separate scaler would cost you around a thousand pounds or more. To think that your £500.00 or less amplifier is going to give the same results is fanciful to say the least. In many cases you would be better using a few more connections and end up getting a better picture.