Post-purchase dissonance, very common affliction. You hear of people buying a car and a week later going back to the dealer and asking the salesman to "sell it to me again".
That being said it's not uncommon to acquire something only to find you're disappointed, what you thought would be a major step up turns out to be barely adequate. Could be the hype was unjustified, more likely it's simply not a good fit in your system/room. That's what the classifieds are for, sell it and move on.
Jeff