Hello, This is a problem that I've been seeing in so many Denon units over the last 5 years. This is one of the most common problems reported on Just Answer and I also see it in the field with my clients who have Denon units. The outputs to the speaker have problems, and the issue occurs most commonly when the units have not been running for some time. My client who I installed a $10k home theater for at his summer home, returned after 6 months to have the exact same problem with his Denon. Upon checking with their service centers, it was reported to be an estimated $200 repair, in which case he chose to purchase a Yamaha instead. I will link to the Denon service center locator if you'd like to inquire about a repair, but this is what I've found out.
Basically if the hard reset doesn't sort the issue, then the unit is in need of service.
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