Is it worth it?

I have a Denon 2802 as my pre/proc and Carver 705 THX amp to run my 5.1 HT setup. Thinking of running separate but not quite sure if it's worth it. Since the kids stay home during summer, pref. is 55% watching TV, 40% movies & 10% DVD concerts. Since my plasma does not have its own speaker, it must rely heavily on the stereo mode of my current HT system, which I though is a little overkill for all those LOUD commercials. Moreover, the plasma unit and the current HT system really generate some warmth in the summer. What I have noticed on Audiogon is that a good preowned THX pre/proc costs at least $1K. Any thought for this dilema?

A side note, why is it a pre/proc unit typically costs more than multi-channel amp as seen on Audiogon? I can find 5-channel amp w/ 150 wpc around $600-800, yet a THX pre/proc run at least $1K?
I know the typical answer would be "it depends", such as what do I want or how much can I afford. What I am trying to get is to feel the responses of those who have similar setup. If you have similar setup like mine, you can tell me whether or not you like it . If you don't have your HT setup to listen to those loud TV commercials like I do, perhaps you can let me know whether you can tell the difference going from AVR+ multi-channel amp to a THX pre/pro unit + multi-channel amp while watching movies. Much appreciated!
THX costs more because 1) Licensing fees and 2)Mandatory specs that drive up system cost. By the way, the audio and video switching is also pricey so drives costs up.

I have an older Lexicon pre that does a nice job, even when it's not in THX mode. If the Denon works well, why switch?

By the way, check out new or used Outlaw products. Their pre/proc is about $800 new.

Thank you for the response. I have looked at the Outlaw, Sherbourn, and ATI. The latter two are like the clones of Outlaw. However, I don't have any experience w/ them. I have seen only good reviews by the professionals for Outlaw and Sherbourn processors. Seriously wondering if there's any bias. So any personal experience regarding any of those three would be greatly appreciated. Back to the ultimate question, why do some people prefer Krell, Parasound, and others over Outlaw or Sherbourn? That is still a mystery to me. Maybe some one can shed some light for me.

Regarding the Denon, your point is valid. Why switch when it works? I'm trying to improve some sound qualities -- solely movies and concert DVDs. However, the key question is whether or not it's worth it since more than 50% of the time is spent watching regular TV. Please, fill me in.
People that buy the more costly pre/pro's are in most cases looking to get higher two channel quality to go with all the DD/DTS stuff. Everything is built to a price point, for the person who does not have a high quality two channel pre mixed in with his hometheater system a more expensive pre/pro may fill that need for him or her. If on the other hand, a person only cares about movies or has a two channel preamp in their system...Why waste money on something you don't need? The Outlaw and others you speak of were designed as great bang for buck units, if they had an audiophile preamp built in...they two would cost much more.

I can't remember ever hearing anything bad about Outlaw units, and I've spoken with a number of people who have them. I've heard one rig - Outlaw 950 processor, their 7-ch amp, with the Rocket speakers (another Internet only seller, don't know which model number but their top of the line 7-ch setup), and it sounded very good. To my ear it was a little bit on the bright side, but that was almost certainly the room, which had a lot of glass on one side. We watched one movie on it, and it was close enough to my vastly more expensive rig (Classe SSP-75, Classe CA200, big Martin Logan panels, etc) that I really didn't care much about the difference.

Then again, I've discovered over time that I my tastes run to 2-ch music, then TV (sports) and finally to movies.
Thank you all. Outlaw or anything similar will do.