DTS Neo is a competitor to Dolby ProLogic. It's a "matrix decoder" used to expand stereo signals to surround sound and to expand 5.1 to 7.1. Whether you use Neo or ProLogic depends on which sounds better to you. Usually you can just set it and forget it. If you have a 5.1 audio system and a signal is already available in 5.1, the matrix decoders do nothing to disturb the sound.
Unfortunately, some TV stations sometimes transmit a 5.1 signal but actually provide audio only in the front Right and Left channels. The matrix decoders can't do anything to expand them to all channels.
Marantz SR7009/7.1.4/FH+TM/DefTech PM1000/LCR+TM amped