I have tested these two receivers and I would like to compose a short comparison. It is difficult to choose between these models since they have many features and functions.
Both models support the latest video standard offering 4K video at 60 Hz with HDR, HLG and Dolby vision. Both models have an ISF certificate. Marantz SR6012 has eARC support (requires firmware updating), HDAM for audio enhancing. While Denon AVR-X4400H has DDSC-HD with AL32 multi-channel processing for audio enhancement. These two receivers also feature an “eco” mode. Both support the Alexa voice technology.
These models support modern wireless protocols and AirPlay. Both manufacturers offer an application for tablets or smartphones that can facilitate controlling. Both solutions have 8 in/3 out HDMI ports. Denon AVR-X4400H has a three-zone capability. Some clients experience troubles with Denon input switching that result in no video output. Both models use the Audyssey technology for audio tuning and tweaking. The Audyssey technology makes both devices very flexible in terms of sound control. Everything necessary for audio calibration is included. Many customers claim that they had no any troubles with the calibration.
Marantz SR6012 has a small round-shaped LCD display with two knobs and a front flap that covers buttons and additional inputs. Denon AVR-X4400H has a bigger LCD display and two knobs on both sides. It also has a front flap with buttons and inputs. It also has buttons to control the menu of the receiver. The remote controller has many buttons and they are located close to each other(some customers find it as a disadvantage). If we compare the weight of Marantz SR6012 or Denon AVR-X4400H, we will see that Denon is a bit heavier – 30.2 pounds versus 28 pounds Marantz.
Denon AVR-X4400H overview
The best receiver is Marantz SR6012. Check Marantz SR6012 price on Amazon