I was wondering if anyone had any suggestion which would improve the sound of this system even more. I have tweaked it for a while, but a few cheap little upgrades can never hurt.
Try isolating your electronics with some BDR (Black Diamond Racing) cones or the like. BDRs come in MkIII (slightly on the warm side of neutral) or Mk IV (neutral) versions. On the net for about $40 for 3 cones. I have them under all of my electronic components including my loudspeakers. They clarify the music quite well. Have fun.