I own the Sim trio, never heard the Theta gear. The Theta gear has way more futures, bells and whistles. I don't know what the feature/performance trade off is. Sim is so balls to the wall, they are too cheap to make a different chassis for the pre/dvd player. I guess a buck saved their goes inside, or so the theory would have it.
The Sim gear is quirky at times. I don't know if this is a trait of other high end gear. The amp is a sheer monster, I have the 7ch one. I am nuts for buying this thing, but the guy that created it is really sick. Runs very cool if this really matters, longer life ect. in theory. I can't clip the thing, not sure if I really want to. When the speakers start to give, game over.
I know DVD is a big waste of money, with the newer chip out next week deal, but man... This thing has a very, very good picture. Really close to HDTV feeds.
I think the Sim stuff is for the really sick hardcore freaks out there.... Myself included
Marty