Maybe not "outperforms", but equally performs based on their tests. I can't vouch for the testing equipment, but I'm guessing they don't deviate from unit to unit. Comparing the one channel test:
The 5805 is rated at 205x1 at 8 ohms, and 344x1 at 4 ohms per S&V.
The 7300 is rated at 202x1 at 8 ohms, and 343x1 at 4 ohms per S&V.
Their 344 is very similar to your 340 watt rating.
www.soundandvisionmag.com/assets/download/DenonAVR-5805lab.pdf
www.soundandvisionmag.com/assets/download/harmonkardonAVR7300lab.pdf
I'm not slamming the Denon 5805 for what it is. Heck, I own the 3805.
But, those figures sure make the AVR7300 look mighty attractive at its price - especially with the video processing and Faroudja DCDi engine.