I am about to buy a model home lock-stock-and barrel.

The attached pic shows where I am going to set-up my HT. It comes with the shown in-wall Klipsch speakers (5.1 system) which I believe to be their higher-end in-wall ones.

The problem is I already own a Def Tech system that includes Mythos ST's (Left/Right), Mythos 10 (Center), Mythos LT's (Surround) which are clearly superior to what is already there.

I am currently running a Denon 4308CI as a Pre/Pro and an Rotel RMB 1075 (120x5) as an amp.

Here is what I am thinking. Would it be advisable to run my DefTech speakers with the Rotel and run the Klipsch directly off the Denon? Including subs, I would be running a 12 speaker system. Is this possible with my system?

FYI, the the ST's would go on either side of the TV and the Mythos 10 will sit on the ledge right under the TV (different one than shown).

The other option is to remove and patch the Klipsch stuff and only use the DefTech speakers.

Thoughts?

You wouldn't want to run two speaker sets concurrently anyway, so yes, remove the inwalls up front and patch those areas. The rear channels could still be used, but your present setup is probably much nicer. Reuse the inwalls in areas that you want to have sound...living room, dining room, patio, etc, and then power that group with the receiver.