I am reposting the steps below. Let me know if it helps.
The last steps that you went through is testing the unit with an ipod. Double check if the selector dial to display has selected the iPod input: VCR (iPod). Are you using a Denon control dock for iPod or a different dock? You can provide me the model of the dock being used.
Just in case you are using a different dock, with the default settings you can connect it to the to the back AUDIO panel using the VCR (iPod) connector using the Audio cable for the dock.
Input source selected should be VCR (iPod)
Also make sure to check the front speaker setup. SPEAKERS have 2 selectable items like NORMAL and CUSTOM and when set to "custom" normal speakers do not operate. This may also be causing the problem. Try switching it back to NORMAL.
Turn the master volume up a bit just to disable MUTING in case this is enabled. Let me know if this helps. I will be waiting for yor response. Thanks