Lot's of questions... So let's break them up.
AV receivers are an evolving technology much like TVs and computers are. Many now include significant video processing capabilities, as well as Ethernet integration for Internet and even PC streaming capabilities. A/V receivers also include video switching for mulitple HD video sources as well as solid audio amplification at levels which can drive large speakers, or small, properly.
Plama & LCDs don't generate HD audio. Computers generally don't either. SACD, DVD-Audio, and Blu-ray Discs tend to have the finest audio quality around. The only thing that can decode that audio is either a player with on-board decoding, or the receiver. Some PCs may be able to do it, but typically they require the appropriate drives and setups to do so. Understand, that by far, most consumers have absolutely no PCs hooked up to a TV at all. Some do, but most do not. So, the traditional cable box/DVD player setup is still the standard, and the easiest way to get surround sound into your home is by getting a surround receiver and some speakers.
It is also the best way to get accurate sound, and improves as your budget does.
That's like saying a car is a car, or a TV is a TV. 5.1 is the number of speakers, it does not define the quality of the speakers nor the size of the speakers, nor the audio or amplification which is going to those speakers.
The cassette tape compared to a mp3 compared to a CD... There are noticable improvements as you move along - and ahead of all of them is Blu-ray lossless audio formats.
Yes, people can work with PC sound boards at full HD audio resolutions and get this level of sound, but you still need the amplification.
I have not seen a TV which outputs analog 5.1 audio to an external amplifier. They DO have digital outputs to hook up to A/V receivers. The best then being Digital surround, not HD surround. The PC can handle full HD surround to amplifiers directly, but as said, the PC is not ubiquitous in the home and doesn't generally handle things like DirecTV, cable TV, Blu-ray Disc, etc. and must be carefully chosen and setup for a home theater application.
A high end receiver is well over $1,000. And, you can get really good quality between about $500 and $1,000. This is the level of quality that delivers multiple HDMI inputs, with HD audio decoding, with upconversion of video, and single cable connections. Audio metering which helps set up the speakers properly in the room is a plus, and solid amplification built in is another huge plus.
Keep in mind, if you price out a good 5 channel amplifier, you are often already spending more than a lot of A/V receivers currently cost.
HD codecs are getting high praise from most people. Anyone with good speakers and audio has stated that the biggest jump which Blu-ray offers over DVD is not at all with the video, but the huge improvement in audio which helps to immerse viewers into scenes are more easily than DVD was ever capable of.
from what i know about computers is that it all comes down to a sound driver.
are these highend recivers just sound cards with well programed Drivers?[/quopte]
That's all almost anything is. Microchips are the core of it, but well programmed AND well built with careful engineering which allows the audio to be decoded through the chip with the absolute least amount of external noise and interference presented into the signal path. Digital to analog converters can be inexpensive, but implementing them flawlessly is as much an art as it is a skill which requires years of audio engineering expertise.
No, HDMI carries data - it carries a LOT of data. Enough data that manufacturers are extremely excited about being able to wirelessly send that much data about 30 feet reliably. That's a LOT of data!
As with almost all data, it is being broadcast over copper wires in a compressed format, then decoded in the receiver, to actual electrical pulses which are amplified and sent to the speaker. They are converted from digital, to analog. Analog doesn't have the same bottleneck issues which digital can have, but can introduce issues, which is why decoding the digital, then immediately amplifying the signal minimizes noise which could affect audio quality.
Optical cables are not capable of the bandwidth necessary to carry HD audio signals.
This is covered in my last post, but is all about the conversion from a 100% digital signal on HDMI to a 100% analog signal on the speaker wire, which has also been amplified at this point.
Good questions really - it's a basic set of questions which many people assume they have answers to but never ask. Now that you've asked, you can get some solid answers.
I would finish with saying that A/V receivers are far more than just audio decoders. They are a value added item which are designed to allow for simple and reliable surround sound implementation. My father, and my kids can both use my surround sound system with the addition of a good remote control. There are no boot ups to wait for, there are no cheap tinny sounding speakers to listed to. They aren't switching inputs of the TV constantly, and they get the best which audio has to offer, in about the easiest way possible.
Very well said!
