I kind of doubt it’s a setting thing … but if you find it is I like to know about it.
Accessories4less.com has ok prices on refurbs. Out of 3 unit I bought 2 were perfect. The third AV8805 took a phone call,to Marantz tech services (to verify that I wasn’t missing something .. ie user error). Acc4less replaced it paying for return shipping. The 2nd unit worked flawlessly.
Not sure what your willing to spend … A 75watt 5.1 denon $350. A 75w 7.1 $450.
I bought a SR5014 a 7.1 (least expensive unit I could find with pre-outs in sept 2020). Currently it’s $750. It’s replacement 5015 is $800.
