I just added a sub to 2-channel and on my Marantz PM7000N you can toggle the subwoofer crossover. (I landed on 60hZ) Oddly adding the sub made my main speakers sound worse, more shrill. Then I tapped the Source Direct button (supposed to remove any tone filters and leave the pure signal) and they sounded normal (great) again and the sub was still doing its thing regardless. I was so relieved.

My takeaway: my speakers (Wharfedale Lintons) needed the full signal to sound their best. It felt like the lowest signals the speaker received colored the mids too on these speakers and overall sounds richer

Yes they get along really well, I’m relieved!

lol it’s a balance I strive for