In audiophile terms it could be a dramatic, never going back, veils removing, you'd have to be deaf not to hear it change. Or, it could be very subtle and possibly not even a positive change. As others have pointed out it can be very system dependent. Based upon your comments I would recommend you not go in the direction of power conditioners. Picking the right conditioner (for you) and pairing it with the right power cord will be a time consuming endeavor. Unless you really want to play with the equipment, why bother?
Am i missing something without a power conditioner?
I need your advice on power conditioners. I know there is alot talked about with power conditioners. But let me explain my situation and what i have. First and foremost i upgraded all my stock power cords. I am using and have a Krell FPB 600 amp with a Shunyata Research Sigma HC power cord. I am using and have an Audio Research Ref 6 preamp with a Shunyata King Cobra Helix CX power cord. And have a Rega ISIS cd player with a Shunyata Sigma digital power cord. I have 1 dedicated 20 amp line with a 4 plug 20 amp wall outlet that my amp and preamp plug into. My question is with these high quality power cords do i still need a power conditioner?