Here's my two cents...... Had the 5600, 5700 and 5800. These units don't even compare to the 49TX. The 49TX is AMAZING plain and simple. The 5800 upgrade is a joke. Denon is taking forever to get this thing done in comparison to the wonderful job Onkyo has done with it's 989 upgrade. The 5803 is basically an upgraded Denon 5800. Denon has done nothing except sit on it's laurels, with the 5800, and slapped Dolby Pro Logic II and THX ULTRA2 onto it. At least Pioneer has invented a complete new unit considering they never had anything close to this in their previous lines before. They even got creative and did what others will follow including Denon. Others will have no choice but to follow with Auto Calibration. In all aspects, the 49TX is the CHAMP until new units are introduced. Down goes Denon, down goes Denon....the knockout punch has been delivered....don't kid yourself....the Pioneer is the real deal!!!