Don't know if anyone else has tried this, but....
I found out you can plug a sound bar into the headphone jack on the remote (RC-EL3) and the sound bar will still work.
I know it sounds funny doing this, but it's not for my regular living/den TV soundbar.
Also, the cord to the sound bar would be ridiculously long and annoying.
I was doing this in my master bedroom.
In there I have your basic classic wall mounted TV, on the opposite wall of the bed.
I have a mini sound bar (about 12-13 inches long) on my beds headboard.
The sound bar is powered by a USB/outlet adapter and has its own 3.5 jack with a 6ft cord for the audio.
I was using a 30ft male to female audio cable that's plugged into the headphone jack on the back of the TV and runs along the tops of the baseboards on its journey back to the bed.
I've used this set up for quite a while. Even before steaming.
One night I was looking closer at the remote and the sound options of the Roku TV menu.
I thought if it can send the TV sound to the remote for headphones, then why not the same for a sound bar?
So I tried it and it worked.
I liked it but......
1. The sound bar jack/plug itself was kind of awkward sticking straight out of the side of the remote.
This could be remedied by using a 90 degree jack adapter.
2. ...and this was the deal killer. Even though the sound bar was running on its own power, the remote batteries were being drained quickly!!
Any thoughts about this?
If you have a remote with an earphone jack, be aware that whenever something is plugged into that jack it turns on the remote's internal earphone amplifier, which uses energy from the batteries and can significantly reduce battery life, whether or not the Roku is streaming anything. Be sure you unplug your earphones when they are not actively being used.
As an alternate means of remote listening, you can install the Roku app (not TheRokuChannel app) on a phone or tablet. In addition to being able to providing remote control for your Roku, it also includes a remote listening function. You can listen via your phone/tablet's built in speaker or via earphones or speaker connected to the device, without adding extra drain to your Roku remote.