In 1987 i used B&W Model 70 loudspeakers with IonoFanes on top. The tweeters made a huge difference especially in the bass reagion, not sure why but somehow it became more cohesive. Even though there were not very present they gave a nice 3d image to the total sound. Later i build some "flames" myself that gave even more spacious sound.
Flame loudspeakers can no longer sold as they are a health hazzard. The IonoFanes and Ionovacs had this issue solved by adding a ceramic tube between the spark and the horn that reacts with the ozon and thus neutralizing its acid effect. The downside is that the tube must be cleaned regularly.