We got the new speaker, and after 5 days are declaring it a success. We bought the ZVox AV157. It has 6 levels of voice clarity, and a squelch-type function to level volume. It plugs into the digital audio output jack on the TV (so you can leave any existing speaker setup in place.)

Here are my observations:
Pros -
- Connection is very easy & straightforward if you have access to the back of the TV. The needed fiber optic cable is included.
- We have a moderate hearing loss situation, so 6 levels works well for us. If yours is more severe, you may want a 12 level version.
- Setting the voice clarity level up enhances the frequencies where voice is heard, and lowers the others.
- We have figured out we can run the surround-sound system (at a low volume) together with the Zvox speaker and get very good sound.
- The speaker itself has an output jack for a subwoofer, but we haven't tried it.
- Low profile, so sits in front of TV or can be wall-mounted easily.
- 60 day trial period so you can return if it doesn't work for you.

Cons -
- At the highest setting, sound is quite "flat" but dialogue is very clear.
- You have to turn the speaker on/off and set it every time using its own remote. Can't figure out if we can integrate it with our multi-device remote.
- Not available in stores, so you have to order it to try it.

This seems like a good fit for us. We ordered from zvox.com, where it is $299 ($100 off with Promo Code VOTE2020 until November second.) Also available on Amazon (without discount) and other models with the same technology are available in both places. Disclaimer - there are other brands available which we did not try. Bought this model on the recommendation of a local audiophile whose opinions I trust.
Sue