CNET's surround-sound buying guide

Upside: Nowadays, entry-level receivers have just about everything anybody needs for home theater. 
Downside: Lightweight build quality; inflated power ratings; poorly designed remotes.

Entry-level receivers can usually do pretty much everything. A good number offer 6.1-channel Dolby EX/DTS ES surround processing--but if your living space is tight, you'll probably use a standard 5.1-speaker package. The 6.1 models add one or two extra rear-surround channels over the standard 5.1 array to create a truly enveloping soundstage in large rooms.

Power ratings run from 50 to 100 watts per channel. In this price range, many of the ratings are inflated, so the specs aren't a good way to judge real-world performance.

Connectivity options are usually adequate for most systems, and they include multiple digital inputs and even component-video switching. Most models also have 5.1-channel inputs for DVD-Audio/SACD.

Upside: Features galore; plentiful connectivity options; midline receivers are more solidly constructed than entry-level models. 
Downside: More expensive; systems can be fairly huge and hog too much shelf space.

Beyond the now standard Dolby Digital/DTS and 6.1-channel Dolby EX/DTS ES surround-processing modes, some midrange receivers offer the latest trick from DTS: 96/24. This technology is similar to DVD-Audio in that it offers high-resolution 96/24 5.1-channel sound, but it also offers full-motion video capability (DVD-A has limited video capacity). Another advantage is that you don't need to buy a new DVD-Audio player; DTS 96/24 will work with most DVD players.

Also, thanks to their superior digital processing capabilities, midpriced receivers offer better synthesized surround modes such as Jazz Club, Rock Club, Cathedral, and so on that can be used to "open up" the sound of stereo recordings.

Onscreen displays (using your TV) ease surround setup and general navigation chores. Programmable remotes control TVs and other A/V components, while more-expensive models employ LCDs or keypads to make universal remote setup easier.

Better receivers also have more inputs, including front-panel digital inputs, digital monitor outputs, and more than one VCR/DVD-R recording loop. If you're a satellite radio fan, you might also want to consider buying an XM-ready receiver. Add a low-cost XM Connect-and-Play module such as the Audiovox CNP1000, and you can receive satellite radio on your receiver. It reduces the clutter in your equipment rack and can be easily connected to new compatible receivers whenever you upgrade.

Upside: At this price range, expect honest power ratings, up-to-the-second features, and great sound quality. 
Downside: An overabundance of features can mean overly complex setup chores.

In a perfect world, power ratings would give some indication of the loudness potential of A/V receiver. But unfortunately, not every 100-watt-per-channel receiver is created equal. What's inside does make a difference, and beefy power transformers and capacitors are not only heavy but also expensive; that's part of what you're paying for here. And while the Lucasfilm/THX certification is a little bit of a marketing gimmick, it's usually a sign of more-honest power ratings.

Higher-end receivers usually offer A/B-speaker switching or, better yet, true multiroom capability. The most advanced multiroom receivers let you control not only the volume but also the source in another room. You might even listen to a different source--say, a CD in one room and the radio in the other room.

A particularly useful new feature is automatic room tuning and setup. Receivers equipped with this capability can analyze your speakers and room acoustics, then automatically adjust for optimum sound quality at the listening position. The most advanced models utilize highly versatile parametric equalization.

Unfortunately, most Super Audio CD and DVD-Audio players don't provide adequate bass management for small sub/sat systems, but some of the latest high-end receivers now perform that function for the players. Bass management is vitally important because it redirects bass from the satellite channels to the subwoofer.

Those with high-def home theaters will be interested in receivers with HDMI capabilities. In theory, there's a lot to like about HDMI: it's all digital, it has the capability to carry multichannel audio and high-definition video signals on a single cable, and it's small, with a plug that is roughly the same size as USB. Toss in an inexpensive cable or adapter, and HDMI is even backward compatible with its digital video predecessor, DVI. The first wave of HDMI-compatible receivers was hobbled with one compromise or another, but newer models are finally delivering the goods at reasonable price points. If you do go the HDMI route, look for HDMI switching (multiple digital video sources); upconversion of analog sources to HDMI, so your older components will pass video through a single output; and full bandwidth support, the ability to pass surround-sound bit streams and full HD video.