Fast & open sounding amp with great imaging 2k

I always liked the Classe CA-2200 which has plenty of power and headroom, is quiet, smooth, resolving & certainly fast. I know the CA-2200 was a great match with Infinity Renaissance 90's. This is a well reviewed amp & you can pick them up in good shape circa $2200-$2500. Btw the Classe pairs well with tube preamps due to it's neutrality and high input impedance (100kΩ).

10-24-15: Zuio
one more thing, my speakers sound best with higher than usual output impedance (my amp has variable output impedance and the best setting is 14Ohm)

If that's the case, then the Classe CA-2200 is not for you, as it has a very low output impedance figure of 0.0055 ohms @50Hz. Good luck with your search!