Brian, assuming that your 333 is still in good operating condition, there's no good reason to expect that replacing it would result in any advantage with regard to just the basic amplification; it should have enough power for your speakers in nearly all circumstances. It is definitely dated with respect to its features, however, and if your budget allows, you should consider a change for that reason. For example, the 333 has only the old basic Dolby Logic; since you have a 5.1 setup it would improve your enjoyment of two-channel sources to have DPLII processing which would send full range stereo ambience to your surrounds. The Audyssey might well improve the overall response in your listening room; results vary.
