Wich Def Tech speakers are best for room size

What is your budget? Is it for 5.0 or 5.1 or 7.0 or 7.1?

Your room is 20' deep. How far back from the screen is the back row? How much room is behind?

Can your space accomodate 3 identical bookshelves for the front?

Edit: Recommendations will almost definitely be to a different sub.

I just purchased the mythos gem XLs and two supercube III. This is a great set up. We watch alot of dvd concerts and it sounds great with these. Movies are great too, but I think they make music sound incredible. We have some BP2006s in another room and they are primarily for movies. We just compared the concert and the difference was noticeable. Alot clearer with the mythos. They do provide a big sound for only have 2 4.5 inch (i think) drivers.

Let me say that I really love my DT PM1000's, PC2000 and BP1.2x's. Do yourself a favor and forget about the PS800, you can get so much better by going with a elemental designs or svs sub for the price. If space is a priority, then consider a mirage onmi S8 sub that is small and quite a bit better performer than the PS800, the S8 even smoked the $700 DT SCIII and the bigger ED and SVS will best the S8.

I have never heard the 450 or Mythos, so I can not comment; perhaps asking in the DefTech thread would help.

I have heard the ProMonitor 1000 ProCenter 2000 setup and it is awesome; rears could be either 2 more PM1000 or PM800; with your space effectively being a 10 x 10 theatre with a 10 x 10 space behind, you could go for 7.1.

Because you have such a high musical content in your listening I would suggest you look at a Rythmik sub (either F12 or F15).

You could get 2 x PM1000, 1 x PC2000, 2 x PM800 and an F12 for < $2K and be extremely happy.