Assuming speakers have been selected to taste that are appropriate to individual room volume and budget, and one has gained sufficient self knowledge in the psycho-acoustic phenomenon in the process of exhausting speaker placement, and room acoustic treatment exercises, then spend on gear to support those speakers.
Of course, if very rare decent source material has not been found as a reference initially, it could all be an exercise in futility. Without it, speaker qualities cannot be discerned, let alone component gear. Much less the subtle mystique of cable and tweak differences. Like a computer, any system is subject to 'garbage in, garbage out'.
Try at least one of the CD's recommended at: http://www.linkwitzlab.com/music.htm (there is nothing to buy there) for a reference. Especially if your goal is hearing the individual instruments as they actually sound live, and to reproduce the concert hall experience as closely as possible in your room, with your system.
