I tried the X3400H for almost two weeks, like it's performance, the look, the weight and the cool operating temperature. Replaced it with the X4400H only because I wanted to try Atmos in the near future, hopefully. This thing runs much warmer.\n\nBoth units sounded incredibly well with 2 channel music whether I used digital or analog inputs, so I expected the X4400H to perform well in my HT room. It was late in the evening after I sorted out the wire jungle behind the wide and heavy cabinet, so only have time to run Audyssey quickly, and just once from the AVR; and started scanning a couple of shows on Amazon and Netflix.\n\nTo my surprise, the DD+Dolby Surround (versus AV8801's DD+PLIIx) sounded different, or "thin" and seemed to have less dynamics. I didn't panic because that's not how it sounded in the two channel system, and from experience, I know how Audyssey could make things audibly worse if not done right. It was really late, so I went to bed, knowing that I would have to play with Audyssey calibrations some more the following day.\n\nSo yesterday I re-ran Audyssey, using the App this time, plotted some graphs to compare the first AVR run and the second App run and plotted bunch of graphs for different combinations of XO. It took a long time to get enough graphs for analysis later. It was late again by the time I got enough graphs. I couldn't wait to find out about the new sound as I could see the different FR in the graphs already. I thought I should watch that same show again before I went to bed.\n\nBelow are the graphs for the two calibration runs, for the FR+FL+Subs.