I think you need to choose a HT playback setting on the receiver when playing the CD player. If you choose 2 channel audio it will literally play 2 channels, even if on the HT setup you indicate you have a subwoofer.
So try choosing something like "Concert Hall" or Theater Sound, etc, etc, and see if the subwoofer works.
Are you running the CD player out of the analog outputs, or are you using the digital output stream? This may also have an affect.
I use the run a (REL) subwoofer both ways. For movies it would feed off the subwoofer preout. I also had the REL connect by the main speaker wire connection, so the sub would work when playing 2 channel audio.
Do you have the Onkyo manual? They are available online.
So try choosing something like "Concert Hall" or Theater Sound, etc, etc, and see if the subwoofer works.
Are you running the CD player out of the analog outputs, or are you using the digital output stream? This may also have an affect.
I use the run a (REL) subwoofer both ways. For movies it would feed off the subwoofer preout. I also had the REL connect by the main speaker wire connection, so the sub would work when playing 2 channel audio.
Do you have the Onkyo manual? They are available online.