best monitor speakers

have a modest system which includes as follows.sony ta-n55es amp,cambridge audio c-500 pre,pioneer elite d6 sacd,marantz cdr 615 connected to a muse tda1543X4 dac,and a yaqin tube buffer between amp and pre-amp.what would be a good monitor/bookshelf speaker to match with this system for around $500-$700 or even less,new or used.listen to jazz,r$b,soul.also listen to clapton,eagles,doobies,and such.thanks for any help!