Changing the speakers will obviously make the bigger difference. Whether that difference is an improvement or not and worth the change, is up to you and your listening preferences. I agree with the other poster who advised you to ask your dealer to loan you the amps for a weekend.
What should I choose??
I have the old B&W 802d's. I also have the older, first generation, Bryston 14bsst amp (now 15 years old). Both of them are performing well and are in mint shape. My question is this: I am interested in the new Bryston 14cubed amp...and I am also interested in the new B&W 802D'3. But I can't afford to do both. Should I focus on getting the amp first or the speakers? Please, I don't need to be told to buy amps or speakers other then the ones I am asking about as I am a big fan of my system. I just know that B&W has reworked their D series and that Bryston has done the same with their amps. thanks, Jim