I don’t know the answer to this because my TV is a pretty ancient Sony 1080p set (the wife refuses to upgrade!), and since we have a Yamaha amplifier/speaker system, the TV sound is set to exit the TV via a digital audio Toslink cable. It goes to a POWERED Toslink splitter. One digital audio output goes to the TV Streamer 2; the other output is the same cable that was originally plugged into the TV, goes to the Yamaha amplifier. So, YES, in this situation, the volume of each output is independently controllable by the TV Streamer/Smart 3D app/HA buttons and the Yamaha amplifier volume control. Does It Make Much Difference What Type of Audio Output Is Used for TV Streaming? - Analog vs. Coaxial vs. TOSLINK S/PDIF?
The TV Streamer 2 was originally something like $260 at Costco, September 2019. For me at the time, there was no foreseeable path to stream directly to my HAs without the ReSound streamer. Now that BT LE Audio offers the possibility of generic connectivity directly to TVs at some time in the future, one does have to calculate whether a Streamer expenditure is really worth it in the meantime or the best option is to wait for a cheaper universal streamer on Amazon, Best Buy, Walmart, etc., or just upgrade one’s TV when BT LE Audio comes built-in. I can’t see ReSound or any other HA OEM blocking direct streaming from an LE Audio-capable TV to LE Audio-capable HAs. That would really be iniquitous.