Upgrade amp. or speakers first?

Thanks everyone. I assumed that the weak link in my system was the amp so that's what I thought I might change first. But it seems you folks, and others that I talked to, think the speakers first. Since that is the case, perhaps I'll go for MUCH better speakers and change the amp later. Thanks for your info.

I'm listening to everyone's suggestions and appreciate your input. I thought I would upgrade the weakest link in my system and from what I can tell, the weakest componet is the Krell KAV 300i. I may keep the N804's for awhile longer. My system ( with Ayre QB-9 ) sounds at least as good as some other ( 804D's without QB-9) systems using McIntosh or Rotel amps. So I thought if it sounds good now, if I upgrade the amp., to Pass, ARC, the new MD-309, integrated or possibly some of the pre/power comb's., I would get even better results. Even though I like the B&W sound, perhaps I should listen to some other speakers
( $7K- $10K).

Thanks for everyone's input and advice. One problem that I have run into is determining how any speaker candidate will sound in my system, fed by the Ayre QB-9 in particular. It made my system much more lifelike. I'm thinking that new speakers may sound great at the dealers but at home, they may be too aggressive or forward. Should I take my DAC and computer with me as I audition speakers, or limit myself to the one dealer that already has the DAC. I mentioned that I heard the 804D's in systems without the QB-9 and the speakers lacked that live feeling that I'm getting at home now.