in general I would say spend more on the speakers, there is usually a larger amount of sound differnce between speakers than between amplifiers.

I'd check out Stereophile recommended components, and speaker reviews.  The non-powered speakers that I am most familiar with in that price range are good but not current models; bookshelf models from B&W and Sound Dynamics.  

I suggest that you look at a Cambridge integrated amplifier and a set of Wharfedale Diamond 10.1 speakers.

The amplifier and speakers both affect sound quality considerably.