@Garz , I have the same receiver so I'll take a stab at this. (Not that I've ever done it, but it interests me.) I'm guessing at your present configuration, and have no clue as to speaker wiring /set-up, so this may need tweaking. (And may not be possible if you are using every output of the receiver already.) Here is my approach.
Start by opening up the manual:
Denon AVR-X4400h Manual
Look under Playback / Playback in Zone2/Zone3
"You can operate this unit to enjoy video and audio in a room (ZONE2 and ZONE3) that is different from the room where this unit is placed (MAIN ZONE).
You can simultaneously play back the same source in both the MAIN ZONE, ZONE2 and ZONE3. You can also play back
separate sources in the MAIN
ZONE, ZONE2 and ZONE3."
So my approach would be to get a second HDMI cable, and connect it to the
Zone 2 output of the 4400h. and
a different input on your TV than currently used for the 4400h => leave that one connected as is. (We are just pretending that Zone2 is in a different room.) So when you want to watch football and listen to your tunes simultaneously just follow the directions in the manual to playback Zone2.
Press Z2 or Z3 to switch the zone mode.
Z2 or Z3 button lights.
Press POWER
to turn on the ZONE2 or ZONE3 power.
The
indicator on the display lights.
Power in ZONE2 or ZONE3 can be turned on or off by pressing ZONE2 ON/OFF or ZONE3 ON/OFF on the main unit.
Press the input source select button to select the input source to be played.
The audio signal of the selected source is output to ZONE2 or ZONE3.
To perform an operation with the main unit, press ZONE2 SOURCE or ZONE3 SOURCE. Each time you press ZONE2 SOURCE or ZONE3 SOURCE, the input source changes.
You'll have to remember which HDMI input on your TV is for regular watching, and which is for Football, but you should be able to handle that.
I hope this is helpful.