Hi Rafael,
Can you give us a little more detail on what you are looking for, sound wise?
And which Audio Nirvana drivers are those? The Super 12"? Super 10"? Stamped or Cast frame?
For my Audio Nirvana Super 12" in the dual port enclosures recommended by David Dicks at Common Sense audio at the time I bought them, I decided to go with a current source FirstWatt F1. FirstWatt is a Nelson Pass company that (eventually) provides all the details necessary for a DIY version to be built. I chose the F1 for the greater frequency extension, particularly in the bass dept. Though now that I am using these drivers paired with dual subwoofers, that aspect that led me to the F1 is less pressing. But the graphs in the 6moons article on the F1 amp speak to nice frequency extension with this unique current source design (which can ONLY be used with full range drivers, not multidriver speakers).
I've also found that I've liked the sound of Gainclone monoblocks with these speakers for a warmer sound.
Since these are pretty sensitive drivers you might also want to look into the low-powered MiniWatt tube amp, which many folks have raved about (6moons and others have reviewed it). Price is a steal. Haven't heard it, but it has a lot of buzz.
Virtue amps also have a devoted following here, and could work here. I also haven't heard this pairing, but I am mighty curious about it. A little more powerful than the other amps I've mentioned. And amazingly, possibly overkill (?). One beauty of full range drivers is the minimal amount of power needed to drive them.
Enjoy your new speakers. Look forward to hearing your impressions. I've been toying for a while with the idea of putting my AN drivers in an open baffle configuration (again, as the low frequencies can be aided by the subwoofers).
