"Most dealers will try to sell their Hi end stuff to make money or clear stock lying with them. Please be mindful of discounts being offered and warranty."
Brother, this is the reason why I did not go to the shop to get a demo of the speaker because I was not aware of all the advice given by you and other colleagues. It is good that you have explained that the shopkeepers also sell old goods. In the last two days. I have watched a lot of home theater related videos on YouTube, I have also taken information about the frequency, watts, (Ω) Ohms of the speaker, and now I am trying to find out how to manually calibrate the amplifier and speakers.
As mentioned put a post on the Denon Owners Thread where users of Denon x3800 can suggest speaker brands and models. Once you get this then ask the dealers for demo of those speakers only and no other models or brands. Once you are convinced then you make the purchase.
Else the other way is to audition speakers you like and make a list with their prices and specs and decide. If you need help in making that list shorter, our FMs will provide suggestion to steer you closer. Most importantly trust your ears!