Some receivers have THX surround ex technology which is basically having 1 or 2 more surround speakers for more surround sound.(6.1 or 7.1)
There are only a handful of DVDs that actually have this sound format available such as Terminator 2.
So the question:
Is there a difference in sound for a 5.1 dolby digital DVD that is heard with 5.1 dolby digital theater versus the THX surround ex theater. In other words does the sound have to be formatted on the DVD specifically as THX surround ex to really enjoy a THX surround ex theater or does the theater bring something extra for regular 5.1 dobly digital dvds as well?

I'm afraid there is no simple general answer.

It's similiar to using DPL on stereo material. Some like it, some don't, which of course depends on the source also.

More important, do you really have the room to add one or two additional speakers behind you?

I have a Denon THX-EX/DTS-ES amplifier.
Rember when you upgraded from Pro-Logic to Dolby Digital it made you say wow! Well EX gets close to that, it made me go through my entire disc collection just to see what new effects would pop out of the new rears.

To answer your question a DVD dosen't have to be encoded in EX to sound good in a 7.1/6.1 set up. Its not how the director intended it, but I like it.

on my model amp if you dont like THX post processing you can select DD 6.1 matrix.

DTS-ES 6.1 discret is AWSOME! although there are only a handfull of discs out there.

If more rear speakers aren't a problem in your home I recomend it.

Unlike Malcolm, I do think there's a difference but it's no way the improvement DD brought us over DPL. If you have the room and the $$$ to buy decent rear speakers it's definitely worth it but don't expect miracles.

No. It's not worth it.

I have a hard enough time finding Decent DTS encoded Dvd's.

IMHO, if you are interested in sound quality, you should probably focus
your funds on seperate amplifiers to significantly boost HT performance,
and not the latest surround sound flavor.

Hook your reciever up to this inexpensive amp and watch your speakers
dance:

http://www.outlawaudio.com/products/750.html


Later, you can add a preamp/processor (there are inexpensive models from
Acurus and Parasound), or just leave the receiver hooked up.

I'm in the wrong business...Since when did $1000 bucks become inexpensive?

In the world of Home Theater, $200 per channel for real amplification
is about as cheap as it gets.

But in my initial post, I was implying to transfer the cost of a new EX
receiver, to a new amplifier instead.

How much is the receiver you are looking at? Subtract its price from the
Outlaw amp, and your bottom line $$ will only be affected by that much.

It becomes inexpensive as soon as you make the transition from beginer and start thinking about the extra tweaks from separates. All of a sudden, what used to sound like a lot of money becomes inexpensive. I know, because I just went down that path. And, oh, does it sound good!