Quad 9L actives, warm, inviting, not overly covered up, very musical, maybe the sleeper in the Quad dynamic line. Used ones are right in your price bracket, high end sound for relative pocket change. Stretch your budget a little (around $6-700 used) for 12Ls which can fill a larger space. Sell your amp and just use the speakers with some decent ICs.
I own both and love them.
I own both and love them.