It makes sense comparing Yamaha RX-V685BL vs Yamaha RX-A8A because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Yamaha RX-V685BL has 7.2 versus 11.2 for Yamaha RX-A8A. Regarding power, then RX-V685BL has such a W/Ohm ratio - 90/8, 150/4 when RX-A8A has a power of 150/8. The THD is the same and is 0.06%.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 384 KHz/32-bit for RX-V685BL and 384 KHz/32-bit for the RX-A8A. Both the RX-V685BL and the RX-A8A support Bi-amping. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
WI-FI modules have the same characteristics: 2.4/5GHz. Rivals from our review have Bluetooth support. The Yamaha RX-V685BL has support for AirPlay, and its competitor in our comparison - AirPlay, AirPlay 2. Only the RX-A8A supports Spotify.
HDMI signal transmission in standby mode is implemented in each of the devices. Both rivals can scale the resolution of the incoming HDMI signal. The HDR standard - Dolby Vision is supported by these receivers.
The Yamaha RX-V685BL has 5/2 HDMI inputs/outputs versus 7/3 HDMI connectors of the Yamaha RX-A8A. The HDMI Audio Return Channel (ARC) feature supports both devices. HDMI eARC is available in each model. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The RX-V685BL supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the RX-A8A. These compared receivers have a built-in phono stage for connecting a vinyl player.
The RX-V685BL supports 2 Multi-room zones, versus 3 for the RX-A8A. It is also worth noting that the ECO mode is presented in each of the receivers. Both RX-V685BL and RX-A8A can be configured using the Setup assistant.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.