what is the weakest link in my audio chain

It sounds really, really good. But since my exposure to audio gears is very limited. I am hoping that you can use your experience and knowledge to point me to the right direction to perfect my system even more.
Thanks

Thanks for the valuable advice. looked like the next upgrade that can gives noticeable sonic improvement with minimal investment would be to use better speaker wires. After that, a power conditioner will bring me even better sonic improvement.
Room acoustic treatment will be my next DIY project.
Thanks for all of your input.

Folks,
Thanks for your inputs.
Before I put up this thread, I have already had something in my mind. I thought you would recommend me replacing the Denon, the speakers, and doing acoustic treatment to the room as the first steps to get a noticeable sonic improvement.
Looks like many of you think my setup is decent. To get better sound than this setup will cost a lot more.
Rleff, without putting another DVD players into my system to do a comparison with the Denon, I do not know how to answer your question. Dealer demo, in my opinion, is not reliable because the rest of the systems are a lot different between mine, or the other dealers. How do I know the sound improvement, or the lack of, is not because of the effects of the rest of the components? I would rather trust Audiogoner's opinions about a particular component. If the majority of you recommend the component, then it it a safe bet that this particular component is worth considering.

I tried a few dealers but none of them was willing to let me bring an item home for audition, even though I promised that if I like the item I will buy it. They insisted that I buy one and if not satisfied, take it back for an exchange for better (more expensive) ones.
My pocket is not deep so most of my gears are bought here or from ebay. That may be the reason why I do not have any established relations with any of the dealers around me.
I wish audio manufactures adopt the model set by outlaw audio, who lets you try their gears free for a month and return it back for a full refund if not satisfied.

I completely understand what you have just said.
Do you think the dealers can have a loaner program like, OK, if you want to try this out, I will charge your X% of the original cost of the equipment times the days the equipment is in your hand. Return the item at the end of the trial period. Extra charge for excess tear and wear.
Do you think this would somehow work?

I took the other route since I could not get an in house demo from my local dealers. I purchased over the last couple of years quite a few gears from local craigslist, ebay, and here on audiogon. Tried them for a few days or a week, then sell them if I do not like them or think there are better components for the money. Sure I sometimes lose a few dollars during this trying and swapping process, but it allows me to audition quite a few gears and I feel it worth it.