Forgive me for sounding like an idiot..I need some help

I have a Yamaha HTR-5790 and it has the THX stuff with it. I do have one question about it. I thought the THX would decode rear surrounds? It does have PLIIx so I can use that but when on the THX Cinema setting I was wondering why there was no rear surround coming out of the those speakers. Am I crazy to think they should be working on the THX setting? Someone please clarify, thanks.

DPLIIx is only active when two-channel sources are playing. When playing a 5.1 or 6.1 source, then the DPLIIx decoder is inactive since those sources are now discrete multichannel inputs, as opposed to a two-channel input that the DPLIIx decoder splits out seven ways.

If you want the back surround channels active while playing back a 5.1 source, then you need to keep the ES/EX decoder set to automatically turn on for all sources. With a 5.1 source, the default playback is without the back surrounds turned on. Otherwise, the back surround channels are only active when the decoder picks up a flag in the audio signal from a 6.1 DTS ES disc or a 5.1 DD EX disc that has the flagging implemented (most early DD EX discs did not have the flagging active).

All that the THX mode does is reequalize the signal. It has nothing to do with the number of channels that are turned on. If you want more channels all the time, then you need to tell your receiver to do that. Check the instruction manual, it should tell you how to activate the back surround speakers.

Thanks Wooch, that explains it all for me. I appreciate it.

"DPLIIx is only active when two-channel sources are playing."
I thought you could lay it on DD 5.1 also.

Actually, I think he is right. I have satellite and it is in 5.1 but I leave it in the DPLIIx setting and get the rear surround channels working just fine. Same thing with my Playstation 2 games as well and DVD's