Experience with adding super tweeter?

I use a pair pf Muratar ES 103b with Duevel Bella Luna: provided you get millimeter precise positioning in phase with the rest of the speaker diaphragms the resulting increase in depth of soundstage and definition of the entire frequency spectrum including bass is nothing less than astounding. The other thing to watxh out for is obviously efficiency, where Duevel and Murata are close enough.,I have no experience with attenuators although they are needed where that condition isn‘t met. In any case well worth the experiment

Goofy idea....unless you get into active crossover implementation or mod the existing passive crossover. 

(It is nothing like blending in a subwoofer without bass management and getting away with it).

The PHASE thing: at 10kHz, the wavelength is 3.4 cm. So moving the supertweeter through that entire range is not too difficult, maybe in 10 steps of 3mm or so. 

But as with any OTHER speaker, the PHASE will only be "correct" (in line with other speakers) for one specifc frequency. So I guess speaker manufacturers may try to get the drivers 'into phase' at the crossover frequency? Or simply just ignore the it since it is OFF the whole time except for one frequency?

The phase thing is best established by trial and error. When it locks in, that is actually quite easily audible

If im not mistaken,

I believe a plasma tweeter can achieve performance well beyond that of a super tweeter. They can achieve 150kHz range without the downsides.

I’ve been infatuated by plasma since I saw demo but the community will be restricted unfortunately as these speakers typically come with six figure price tags

no inductive voice coil, no inhomogeneous magnetic field, no resonance-bound membrane, no mass-spring system vibrating back and forth, and no non-linear suspension. All there is light and air.

also can be hazardous unless designed brilliantly