what is the weakest link in my audio chain

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.

My thoughts were just to try another source if your were interested,denon makes a very nice product designed for performance at certain price point;modding the unit,going new or using a seperate external d/a would give you some areas to think about trying.
If replacing: a dealers audition in your system would be the best comparsion,lastly the external d/a is a route I took once and it worked out very nicely as there are always several higher level d/a's for sale on this site;letting you move up to the next level.

You said that the problem with trying other components was that the rest of the dealer's system wouldn't necessarily match yours. If you deal with a decent A/V retailer (not BB and CC) most will allow you to take any specific component home to try in your system in your listening room. They'll usually write it up as a sale on your credit card just as insurance that you'll return the unit in the time specified. Once you develop a relationship, even that restriction usually disappears.

I too had an ageing sytem that needed upgrading and I wasn't sure where the best bang for my buck would be. By trying a couple things, I quickly could hear that, for my system, the biggest improvement came form a substantial upgrade in my souce player. Good luck, but be forwarned, upgrading is infectious.

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 tried a few dealers but none of them was willing to let me bring an item home for audition, even though i promissed that if I like the item I will buy it." (Benqsun)

Alright here's a little insight from someone who's worked in a few high end audio stores over the years.
I think what you're experiencing is that retailers have learned over the decades, that home auditions are about 95% BOOMERANGS! Auditions, with no strings attached, DO NOT work! - And the product is MOST ALWAYS destined to come back to the store. Why? Because any audio enthusiasts who's interested in experimenting with his system, will continue to do just that! - EXPERIMENT! And he'll be on to the next line of products he's considering to see what else is out there. That IS the way it happens, regardless of what any customer may tell you up front.
Why would someone running a business, that's already extremely difficult to keep profitable, offer a "try-out service" for his products? Time is money, and that's money well wasted basically. These types of customers (audiophiles and audio/video enthusiasts, alike), from my direct personal experience, are largely curious, uncommitted at that point(I mean they want to try the product because they're uncertain about ALL their options), and simply running a "science project from the library", basically! These are not the kinds of customers that will pay your bills, trust me!
That said, I ask you, "would you loan equipment out to people you KNEW were not going to buy anyway?" If you answered yes to that, you might wanna consider another source of income. Believe me!

"They insisted that I buy one and if not satisfied, take it back for an exchange for better (more expensive) ones."

Andrew Singer, from Sound by Singer on the East Coast US has been using this approach for years. And he's been one of the very very few ultra high end audio salons that has mad it work! He's no dummy when it comes to making a sale, and getting products to the customers. I can tell you that much. He understands that if you simply let the customers, say, borrow your Porsche for a week - to have fun with - and you don't make them commit to buy one model or another if he let's them borrow the car (so to speak), they will return the Porsche with a simple "thank you", and be on their merry way!...not only that, but leaving you left having to clean the sucker, and fill in all the dents and scratches, when you're done having your jollies with it!

Business is business, basically. You can't let kids run through your store, unrestrained, and hope to make a profit! If anyone is interested in doing a "trial run" on some gear, and tinkering like an audiophile, they can EASILY buy ANYTHING AND EVERYTHING - for cheaper, mind you - over the internet!
Just don't expect your local mom-and-pop high end AV store to offer a "try-out service", a "loaner program", a 30 day (Best Buy), no questions asked, return policy (after you figured you really need the rent money, or your wife says she would rather to go on a vacation with that money instead) and expect to be in business the following year.