Ok, am fairly getting into the whole home cinema thing now. Bought myself a couple of years ago what I consider to be a decent receiver (Harman Kardon AVR 5500). But the more I read about amps/receivers, the more confused I'm getting. What is the difference between: preamp, power amp, high power amp, multi channel amp, receiver? I'm getting the impression that purists scoff at receivers, why? What are the alternatives? What's better about them than receivers? Also, formats. I bought my HK thinking 5.1 sound was brilliant and about as good as it would get after my previous sony dpl receiver from years ago. Now I see all these 7.1 channel receivers coming out. What supports this? I don't know any dvd's (my main use of receiver) with 7.1 channel soundtracks. Will there be 8.1 channel sound next with a central rear speaker? Computers are easy relative to this, you just by the latest technology every couple of generations and are usually fine. When will the next generation of sound channels/formats be coming out if i don't upgrade to 7.1? Also (sorry for going on). THX. I understand about Dolby Digital and DTS being sound formats, but THX appears to me to be more of a quality level than a format. Pros and cons anyone? Seems pretty expensive for a guarantee of quality! Any answers appreciated!