The challenge in choosing an alternative to the DX25 tweeter is to find one that combines good sound, a low resonant frequency, and the required 93 to 94dB sensitivity. Pick any two, but if you want all three there are few options other than expensive horn tweeters. One dome tweeter that looks like it might work (with a different crossover) is the Morel MDT-37. It's more than double the price of the Vifa. I have no idea whether it would sound better.I suspect the most cost effective way to upgrade the sound of the Studio series speakers is to upgrade the tweeter cap. I replaced the Solen with a Sonicap which, to my ears, reduces the treble glare a bit. A matched pair of 10uF Sonicaps costs about $45 with shipping.