Still working my way through this very question. What I have learned so far:
With a Sharp 70LE732U, you can connect a remote sound bar via an optical cable. The volume on that connection does NOT vary with the TV's volume control. You adjust the volume on the sound bar using the sound bar's remote.
There is a second connection mechanism...using a 3.5mm mini plug (TV end) and standard RCA (Red and White audio) cables on the sound bar end (I am trying to use a Bose 1SR Sound Bar). That requires an adapter to convert the mini plug to RCA plugs. I plan to try that. There is an option on the TV to cause audio out to be "variable" instead of "fixed". For sure that option does not affect the optical cable...but I am hoping that it does cause the volume to vary over the RCA plug connection type. If so, then that would be a way to have the volume vary on the sound bar by the TV's remote.
Otherwise, I do have the SR1's remote (which is nice) configured so that it will also control the Telus Optik DVR. So using that remote instead of the DVR's remote is a way of avoiding the use of two remotes.
At the research level...there is something called CEC protocol which apparently is meant to have remotes interoperate. I believe CEC is branded by the manufacturers...so Sharp Aqua-Link or some such. My TV is supposed to support that, but not sure the 1SR does. Anyway the TV and Sound Bar do not seem to cooperate right out of the box.
Right now, my default solution is to use the 1SR's universal remote to control both devices. That is acceptable. But I will also try out the RCA connection at some point.