Calling on the experts and oweners of these Yamaha's. I was given the 640 for Christmas and have not really tested it much yet,as I returned the Bose speakers that were gifted as well, and have not replaced them yet. My dealer is willing to make the swap up to the 1400 which will cost me $200 extra. My question is, should I go for it considering that I'm still trying to save up for the new speakers(what I don't know yet). I know the 1400 is a step up, just wanting to know exactly what the significant differences are in these two models. I probably should mention that my room is 16x20 with trey/vaulted ceilings and hardwoods, which will probably make for some difficulties with acoustics. I'm thinking the extra power of the 1400 may help out some. Although I have not settled yet on speakers, I know I will be going with bookshelves. Thanks for any help. ** By the way, since finding this forum right after Christmas, I also returned the 4:3 60 inch Mitsubishi that my wife gave me for a 65413 widescreen. The upgrade -itis is killing me already.