Various versions of HDMI
 

Richard Tobin wrote:

Can you adjust the volume using the TV's remote? Avoiding the use of
two remotes for normal TV watching was my main reason for using the
HDMI return channel.

My amp has ARC, but the TV doesn't, however using CEC allows the amp to
turn on when the TV does, and the TV remote's vol+/-/mute buttons
controls the amp's volume.