I appreciate everyone's advice offered. I had assumed that perhaps the amp would offer the most immediate improvement, though the idea of replacing the pre-amp also makes sense. Even though I have the two HT-capable components, my setup is fully 2-channel. I actually want to move to a pure 2-channel system, since it best reflects how it is used. I now have some research ahead of me to determine the best amp and/or pre to spend my money on.
Thanks again to all who took the time to contribute their thoughts.
Thanks again to all who took the time to contribute their thoughts.