First of all, congrats on being a Viva owner! That's a wonderful little amp you have there.
Of the speakers on your list, I like the Kharma. I sell full range electrostats, and the Kharma 1.0 is almost unique among dynamic speakers in its price range in approaching the coherence of a full-range, single driver electrostat. All I can say is, they got the details right.
But I don't think any of the speakers you list would be an outstanding match for the little Viva. Yeah I know it's far more powerful than its conservative 12 watt rating would suggest, but you really need a dedicated high-efficiency speaker. Unfortunately, there aren't many small, really good-sounding high efficiency speakers out there.
If what you're looking for is a speaker that's more visually subtle than the Duo, even if it's bigger than a Watt/Puppy, then I have a recommendation. That's the Classic Audio Reproductions T-3. The T-3 is shockingly natural sounding, and does many things better than even the Trio's. I'm not normally a fan of high efficiency speakers, but this speaker is timbrally correct, non-fatiguing, and has superb dynamics and natural tonal balance across the frequency spectrum. In my experience it does not image as well as the speakers on your list, but it sounds more like live music than any direct-radiatior dynamic speaker I can think of. As such, it is worthy of the Viva.
The T-3 is 46 inches high, 24 inches wide, and 25 inches deep. The speakers have a classic, 50's-ish look, but use ultra-modern Pioneer TAD drivers.
I'm not a dealer for Classic Audio Reproductions speakers. Yet. Their website (http://www.classicaudiorepro.com/) is pretty sparse, so e-mail me if you'd like to know more. I think the T-3 is available with 16-ohm drivers, which might make the little Viva even happier.
Go over to the Audio Asylum and do a search of the High Efficiency Asylum for "Classic Audio Reproductions". You'll find that this relatively little-known line has the highest respect of those who have encountered it.
Whatever speakers you end up with, may they bring you years of joyful listening.
Best of luck in your search.
