Hi Young_Hov,
Looks like you're ready for a serious but exciting wholesome hobby (Audio). Gazing at your current set up, it would be good if you change your speakers first. Go for some audiophile-grade speakers. Pioneer HPM-60? One of my friends, Eriv Villanueva, used to have that one so I know well enough how that sound (typical Japanese sound - boomy and bright). Looking back, the first speakers my dad bought (when I was still in Grade Six) were a pair of Pioneer HPM-120 (good bass, but overall still a far cry even from todays budget audiophile-grade speakers).
But let me ask you first: what type of songs do you play in your system? Once I see that, I can have an idea what to recommend to you. And secondly, how much is your budget for your next indulgence? Tell me also how big is your audio room (L x W x H).