Belles 350A,ref, with audience PC, best amp in your price braket,period:
Juancgenao (Threads | Answers)
It's hard to disagree with this recommendation, although I'll never say anything is the best.
I'd add a pair of used Belles 150A Reference monoblocks to this suggestion.
The NuForce Ref9SE V2 mentioned earlier are also excellent, but you need speakers with a relatively flat impedance curve to take full advantage of the NuForce amps, otherwise they might be bass shy since they do not double power output as impedance is halved. This was my experience with them.