what benefit would i get if i have a dedicated AV processor vs a receiver that has preouts?
If you have an AV processor, do you realize you would then need to purchase at least a five channel amplifier for your HT? I'm not certain of your experience level so if that offended you, it was not intended. If your AVR has pre outs, you have the option of adding an amplifier at a later date but is not required up front.
If your new to this and you have an AVR with pre-outs, try listening to the system for awhile with just the AVR and forget about an amp for now. Take some notes while watching a movie or listening to music. Are there things that "seem" to be missing, impact is not there or just general observations.
After awhile, you will know if something needs improvement. Since your AVR has pre-outs, you can then add an amp if you want more slam or dynamics from your system. Which amp? who knows
That question is like boxers or briefs. But, an amp can bring a new dimension to your listening pleasure.
One advantage I see to a separate pre/amp system is future proofing. Once you decide on an amp you like, it can last a lifetime. The new formats in sound and video always coming out makes a pre obsolete very quickly. If your not into the latest and greatest bell and whistle that may not be of concern. But if you're an early adopter, pres are disposable in a warped way of thinking.
My HT process went like this: AVR>AVR & AMP>PRE & AMP. I've had the same amp for 15 years in my HT but the pre's have come and gone depending on the audio and video formats available and desireable.
Gordon