Though not a true surround sound system, simulated surround sound has its advantages if you're on a budget or in a small space.
Simulated surround sound may refer to two different types of surround sound emulations: simulating a surround sound system with only two speaker channels, or converting a stereo audio source to a simulated surround sound experience. Depending on which you're trying to achieve, different technologies create different results, so it's important to shop around. Keep in mind that some purists abhor these simulated surround sound methods, so if you're critical of your sound quality or playback, you may be disappointed by simulated surround sound.
Two-channel speaker simulated surround sound
This sort of simulated surround sound is sometimes the best choice if you live in a very small apartment or studio, if running wire for surround sound isn't possible or if you need to keep your sound levels to a minimum. This type of simulated surround sound utilizes just two speakers to produce an audio experience similar to surround sound. You'll never experience movie special effects in quite the same way as with a full surround sound system, but it can be a good choice if you simply want your sound to fill up a room and provide an immersive experience.
Most notably, DTS has made a foray into simulated surround sound with its DTS Surround Sensation technology. DTS has a reputation for delivering top-notch sound, and Surround Sensation technology delivers what you'd expect from a DTS experience.
Two-channel source simulated surround sound.
Two-channel source simulated surround sound attempts to create a fake surround sound from a simple stereo source. You can use this simulated surround sound with two-speaker simulated surround, but the two contexts are distinctly different and each can be used without implementing the other technology.
For example, if you've got a full surround sound system and want to listen to your two-channel audio CDs on all your speakers, you can utilize a simulated surround sound mode on your receiver to achieve this effect. Depending on the receiver, it may break up the sounds and play them from different speakers or play the same channel on multiple surround sound speakers at lower intensity. While this style of simulated surround sound can fill up a room, audiophiles and music purists often deride this method of playback because the audio doesn't sound how the composer or producer intended. You can, however, achieve some very interesting effects, especially if your receiver has a "hall" or "club" option. These modes simulate the spaces involved in these venues and the way the sound would travel in such places, which can be a really interesting way to enjoy your music at home.
For HDTV, you've got a choice in connecting components to your display. Comparing HDMI to component video.
Contrast ratio can give you an idea of how HDTVs compare, but there's more to the number than you think.