Some weeks ago the sub stopped working. Thought dog had chewed the coaxial driver cable, but not shorted (now). Tried another sub w/o success.

Hi, I went to the Denon website and they have no documentation there for your receiver.
But do not frown, I have some good suggestions for you.
0 Don't beat the dog. After all, it's their job to chew things.
1 Get a new, un-chewed cable and see what happens between the sub output and the sub woofer. If it works, your in business. If it does not work. Don't be discouraged . Go to step #2
2 If the sub output on the Denon has failed, and everything else is good. There is another way to use your sub.
Install a patch system using the Headphone output from the front of the Denon. It may seem odd, but it works exceptionally well for the following reasons. It works on all signal sources. So if you are not playing a home theater source, you still have the use of your sub.
You will need the following adapters.
1 A Male stereo phone jack to female mini-phone jack. (Something that would accept typical small headphone sets such as those on an iphone).
2 A stereo "Y" connector that that has a single stereo male mini-phone jack that has two "RCA" female jacks.
3 A simple RCA male to male stereo cable pair as is commonly used to connect CD players, etc. i.e. separate red and white RCA connectors at both ends.
1 and 2 above may be available as a single unit combined with each other.
Take these adapters and connect the Item 1 into the Receiver, Item 2 plugged into Item 1, Item 3 plugged into Item 2 and finally the other end of Item 3 plugged into the two female RCA jacks mounted onto the back of the sub-woofer. If the sub only has one female RCA connector, get a RCA "Y" connector that has a single male end to 2 female ends.
This setup will work perfectly with any sub. The reason is as follows. Most decent subs have an adjustable high frequency cut off. So you can vary it from about 20Hz up to about 140 Hz.
I recommend that it is cut off at 80 hz. This way the bass transition is usually seamless between the woofer and the rest of the system. .
Then adjust the woofer volume control in a similar manner.
If it all works out, give the dog a treat and enjoy yourself.
I really hope this helps, I love my sub woofer as well.
Let me know how this turns out.
If you have any questions please post them on the site and I'll get back to you ASAP.
Best Regards,
Mark