When you have exhausted speaker placement, and room acoustic treatment exercises, and are satisfied with your speakers ---selected as appropriate for your room volume, and having gained sufficient self knowledge of the psycho-acoustic phenomenon in the process, spend on the gear to support the speakers, followed by the subtle difference in cables and tweaks.
Of course if you haven't found some very rare decent source material as a reference, it could all be an exercise in futility at that.
Try at least one of the CD's recommended at: http://www.linkwitzlab.com/Music for a reference 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.