The Onkyo HT-R391 is a 5.1-channel AV receiver that was released in 2017. It has a power output of 100 watts per channel into 8 ohms (stereo), a frequency response of 20Hz to 20kHz, and a total harmonic distortion of 0.08%. It has a variety of inputs and outputs, including 4 HDMI ports, 2 component video inputs, 2 composite video inputs, 2 S-video inputs, 5 analog audio inputs, 2 optical digital inputs, and 1 coaxial digital input. 
 
The HT-R391 supports a variety of surround sound formats, including Dolby Digital, DTS, and DTS-HD Master Audio. It also has a variety of features that can help improve the sound quality of your home theater system, such as Onkyo's Dynamic Audio Amplification and the Audyssey MultEQ XT room correction system.
The HT-R391 is a well-rounded AV receiver that offers a good balance of features, performance, and price. It is a good choice for those looking to build a high-quality home theater system on a budget.