i get the picture BUT NO SOUND - HELP!!!

You should get both audio and video from the HDMI cable. However, if your TV audio output is connected to an A/V receiver, some TVs will not pass HDMI audio input through to their optical audio outputs, in which case you would need to use your TV's speakers.

Check the audio settings in the ATV and your TV and make sure everything is set correctly (including the volume). If you still can't find the problem, try a different HDMI cable.

Check your Denon setup and make sure you have it configured correctly for that input. You may also be able to leave the HDMI cable connected to your TV and connect an optical audio cable from the ATV to the Denon to get audio through it.

Your receiver will likely let you map different audio and video inputs to different outputs, if you have these settings wrong, it may well give you the issue you describe.

I'm not familiar with your Denon specifically, but my Onkyo A/V amp has a settings menu for each input. Check the settings for the HDMI input you have the ATV connected to and make sure they are correct for your TV.

Also, as I mentioned previously, you could connect your ATV back to your TV directly with the HDMI cable, then connect the optical audio output on the ATV to an optical audio input on your Denon, then make sure it is selected when you watch the ATV to get digital sound.