Denon 4500 is a good model, supports the upcoming IMAX Enhanced. You can also consider Marantz 6013, that also a 9.2 AVR with 11.2 processing, also supports IMAX Enhanced. Price will be less than Denon 4500 and Marantz considered to be more musical.
Since you are upgrading from Sony HT, I don't recommend Onkyo 9800.
It is better to select good products from each category and integrate them. For e.g.
AVR: Denon/Marantz
Speakers: Focal/Emotiva/Polk/KEF/SVS
Subwoofer: SVS/Velodyne/REL
As RajithKumar suggested you may go step by step, because after buying 4500H you may not have good amount left in 1.5L to buy matching quality speaker and subwoofers.
Since you already visited Profx, you can visit DNI, HTStore, The Home Cinema etc.
Since you are upgrading from Sony HT, I don't recommend Onkyo 9800.
It is better to select good products from each category and integrate them. For e.g.
AVR: Denon/Marantz
Speakers: Focal/Emotiva/Polk/KEF/SVS
Subwoofer: SVS/Velodyne/REL
As RajithKumar suggested you may go step by step, because after buying 4500H you may not have good amount left in 1.5L to buy matching quality speaker and subwoofers.
Since you already visited Profx, you can visit DNI, HTStore, The Home Cinema etc.