Are you sure the Denon can drive a 4 Ohm load, cause look at this:

Right on the back of the 3803 is states: 6-16 ohms for speaker impedance. In other words, it would be safe with an 8 ohm speaker, and 6 ohms would be pushing it.

http://www.crutchfield.com/cgi-bin/...3803&display=XL