There's no option on the sound bar to do so but depending on TV you may be able to. I have an LG C8 and I can check the options on there when home. I vaguely remember an option on my TV to play through both. This may not help if your not using a similar webos TV.

my very high end TV's speakers

I doubt your TV will sound better than a soundbar.

Help us out. If your goal is to use the TV speakers, is there a reason you wouldn't go with something like the Nvidia Shield TV?

I sometimes like to play music over my sound bar while gaming over the tv speakers or through a headset (with in-game music muted). Anyone have any clue if I could do this with the JBL link bar? Cast music to it while the tv is on, say playing PS4?