The STR-DH770 delivers surround sound using only the front speakers with Front Surround DSP technology, as well as compatibility with the latest 4K 60 Hz video standards with HDR. At a 6-ohm load and with two active channels, the receiver provides only 90 W/channel versus 145 W/channel in the STR-DH790. It would also not be out of place to mention in the comparison, Sony STR-DH770 vs Sony STR-DH790, that STR-DH770 does not have support for the second zone. The device is capable of decoding all current multi-channel audio formats, including Dolby True HD and DTS-HD Master Audio.
Sony STR-DH790 is the 7.2-Channel receiver that supports Dolby Atmos and DTS: X technologies and delivers comprehensive surround sound. The receiver has native support for a 5.1.2-channel surround sound system, which provides realistic sound from all sides. In addition, with support for 4K HDR, you get great picture quality. For sound tuning, the receiver has a system of automatic phase matching, which synchronizes the phase characteristics of the speakers in the front left and right channels so that all channels are perfectly combined with each other and create high-quality surround sound.
The Sony STR-DH790 is better receiver in this comparison. Check Sony STR-DH790 price