Experts: Why is preamp important?

Having just recently going from an Outlaw Model 990 home theater processor to a Pioneer VSX-74TXVi which is similar to your Pioneer receiver which I am using as a home theater processor, I would say the preamp is very important. At first I didn't think going from a separate processor back to a receiver would be a big upgrade but in my case it was. Most of the upgrade in sound was probably due to the more sophisticated acoustic measurements with the Pioneer vs. the basic speaker level adjustments with the Outlaw. But also having the iLink ability with my Marantz DV-9600 to capitalize on the jitter-free transfer system helped as well. I am using a Parasound 5 channel amp to power my Magnepan speakers and I can say that the separate power amp helps with the sound as well. Wider soundstage, more detail and better dynamics vs. the Pioneer's power amps. If you ask me which has the greater impact in the sound quality, I would say the preamp in my case. Using the Pioneer's MCACC mic system is several levels higher than the Outlaw's basic mic system. But there are positive audible differences going to a separate power amp with your Pioneer as well.

French fries: I'm a little slow on the uptick. Who do you mean by "you know who"?
Slbenz: your preamp improvement seems to be relative to a HT environment. Did you see equal improvement in 2 chnl sound? I didn't think the MCACC system (and it's equalization) impacted 2 chnl listening much, and not at all in "direct" mode.
To all: the question remains - am I "double processing" the signal using pre-outs to an integrated, and how much negative imapct will this have? Would I be better off with an amp switcher instead?

Atmasphere,

I assume your preamps are correctly designed to render interconnect differences moot. I can assure you that there are reviewers out there who will let you know that interconnects do indeed make a difference with your preamps. Now who do I trust....reviewers with golden ears, or the manufacturer....hmmm :)

Jeffkad,

Yes, the Pioneer did affect my 2-channel is a positive way as it did my 5.1 Magnepan set up. Mid and low bass was much improved and the highs were not as harsh. In regards to the "Direct Mode", I think you mean the Pure Direct mode which doesn't take in account the MCACC equalization. Direct mode still uses the receiver's processing.

Yeah, I-don't-know-who either.
I would say that running the signal through 2 budget priced preamps is going to do more harm than good. I would even say that running the signal through 2 high end pre-amps will probalby detract noticably fromthe sound, compared to just 1 preamp. (Althogh I have not tried an Atma-Sphere pre-amp)
Ralph - Does the interconnect between the source and the pre-amp run into the same problem as if you were to run the interconnect directly to the amp?