CNET's quick guide to surround formats

DTS is an alternative to standard Dolby Digital. DTS uses less compression than Dolby, and some audiophiles believe it produces richer bass and greater dynamics. Virtually all receivers and home-theater systems include DTS processing.

It's similar to Dolby Pro Logic II, but Neo:6 produces up to 6.1 channels of surround vs. PLII's max of 5.1. You can use two rear-center speakers and bring the speaker tally up to 7.1. Like its rival Dolby format, Neo:6 is fully compatible with all stereo sources.

ES adds one (or two) rear-center-surround channel speakers to the standard 5.1 array and can deliver more enveloping surround effects than standard Dolby or DTS. Unlike EX, Dolby's matrix, 6.1-channel format, DTS ES offers a fully discrete back channel for more precise localization and imaging. But that advantage over Dolby EX holds for only DTS ES-encoded DVDs; currently, a mere handful of titles is available. To utilize this format, you'll need an ES-capable receiver.

DTS HD, previously know as DTS++, is DTS's answer to its rival surround sound format. It supports unlimited number of surround sound channels and delivers audio quality at bit rates extending from DTS digital surround to lossless. Although technically superior over its Dolby counterpart, DTS HD is selected only as an optional surround sound format for Blu-ray and HD-DVD. The new DTS format is backward compatible with existing DTS decoders and supports down-mixing function for converting DTS HD signal to 5.1 and stereo formats.

DTS 96/24 is similar to DVD-Audio in that it provides high-resolution 96/24 5.1-channel sound, but it also offers full-motion video capability (DVD-A has only limited video capacity). Another advantage is that you don't need to buy a new DVD-Audio player; the DTS 96/24 signal can be fed by any DVD player via a single digital cable to DTS processors in the receiver. To get the best sound, you need a receiver with up-to-the-minute DTS 96/24 processors.