i wrote an article on these devices which greatly improved my listening room. They are fairly affordable so I wanted to share the article in case one want to have a less intrusive way to improve room acoustics.
https://parttimeaudiophile.com/2018/12/28/synergistic-research-hft-and-factory-tour/
https://parttimeaudiophile.com/2018/12/28/synergistic-research-hft-and-factory-tour/