Thoughts on adding a Super tweeter .

Cjsmithmd,et al...The reason for my post was for a couple of reasons(thanks to all,for responding).I have heard the Townshends(I like the Muratas,but they come in too low,to consider)in a fellow music lover's wonderful set-up.He was sporting the "shockingly good" Sonus Faber Extremas,a design long since gone(what a mistake,to discontinue these),and since I believe those had a tweeter roll off of 17khz,he gave the Townshends their day in court.BOY,the difference was NOT subtle.Better air/texture!For sure!Much more palpable.
So,with the non- stop talk of Berrylium/Diamond tweets,I simply felt,maybe,I could get that extra something,I read so much about.Bear in mind I felt my own speakers,which are flat to 25khz,had more air/extension,than the stock Extremas,but the Townshend demo was amazing.
Now,some time ago I added a Rel Stentor sub,to integrate with my system.I have my speakers almost 9 feet out from the rear wall,and have a very deep "stage presentation".However,as my speaker is a sealed box design,I suspected I could gain a touch(that's all I was looking for)of added heft/depth,in the lowest frequencies.
My friends were all dead set against this,as my speakers are amazingly fast,and articulate in the midbass.They did not think I could get a good blend.They were wrong,thankfully.Though it took me a long time to get past the "WOW I have loads of bass,and isn't it fun" factor.The blend is now,absolutely seamless,and hence my having a sneaky suspicion that I could pull a "touch" more off,in high freq air,or whatever.
Believe me,I could be making a mistake here,and am aware of it,as the Townshend comes in,and will overlap my own tweets by about 5khz.This can be trouble,and if my bass experience is an example(any overlap in low frequencies came off as "tubbyness") I can easily screw up something I have no actual criticisms of.YET,AND YET...I am always trying to push the envelope,and believe in my system.This could spell trouble,but as I see it,I may have to scratch the issue,or take a trial run.
I hope to get some meaningful feedback by those(few?)who have possibly tried or heard a supertweeter on a speaker with an,already extended high freq response.
Thanks,so much.

Tvad - You are right of course, I forgot about the high-res media.

Cj - Your experience is what I think is supposed to happen w/supertweeters. The ultrasonic frequencies they reproduce aren't supposed to be heard by themselves, but by their interaction with other frequencies. The best analogy is if you play the same note on 2 guitar strings that are slightly out of tune, you will hear a low frequency wavering. This is called a beat frequency by acoustic engineers (and has nothing to do with the beat of the music). The supertweeters are supposed to produce audible results by modulating the rest of the frequency spectrum. In order to do this, though, they must be fed a signal that represents the ultrasonic content of the original musical event. This is not possible with Redbook, but is with hi-res and probably vinyl

I agree with Muralman1. I have recentlty tried Super tweeters and I think they overlap the other Speakers tweeter's too much.
I also think it threw off the balance of the mid and low range of the main speakers.
But, I was experiminting with vintage Rat Shack Super tweeters. (5K to 45K hz 96db). I knew the original crossover network 5k was too low, so I took all that out.

I tried changing crossover points all the way up to 18,000 hz, and I also tried first order and 2nd order slopes and it still added too much overlap.

So unless someone will let me try a Murata, I am done with that idea for now.

Tom Port uses Townsend Supertweeters on Legacy Focus speakers. He brought over just one and attached it using duct tape at the inside on my right channel Focus speaker at the level of the existing ribbon tweeter. We listened to vinyl and immediately heard the increased airyness of the recordings. The speakers disappeared with the supertweeter (and I have Hallographs behind the speakers in a 25' X 21' X 12' high room with the speakers 6' from walls). If one worked wonders, two should be fantastic. However, the setting was at the low end at 2 (out of 10) because the Focuses are rather efficient at 96 to 98 db/watt. So, this is the first time I've heard a supertweeter blend so well with rolled off speakers (Focuses have a very pleasant rolled off highs, at least the first model from the 1990s did, maybe the new ones have better ribbon tweeters).