I also listened to the VIVA Verona at Victor Goldstein. I also had the pleasure to meet Amedeo, Viva's engineer, when I was at Victor's place. The Verona blew my mind! the best amp I have ever listened to. Best components, no feedback, single ended, point to point... I would go on and on for ever. It will definitely fit well with the Avantgarde. I would give Zingali a try as well or even the Triangle Magellan. In my opinion, the VIVA is simply the best amp one can buy nowadays. I wish I could afford it!
One more thing. Don't worry about the power whatsoever. The truth is that though this amp will shine with high sensitive speakers (ie. Avantgarde, Zingali, Triangle), it is able to deliver enough power to run almost anything. Check the Viva website for advice. They also know a great deal about speakers.
Hope you enjoy it.