I had decided on buying the RXV630RDS, but was too slow on the uptake and so missed out on getting my hands on one (hens teeth and all that). I am therefore keen to get my hands on the 640 model. However, I was wondering whether it might be better idea to get the 740 instead. What are the differences between the 640 and 740? Is it worthe the extra money to go for the 740? I know that the power is greater but is there anything else of note that makes it an obvious choice? I have the Kef KHT 2005.2 speakers and wonder whether there will be any noticeable difference between the 2 amps. Has anyone any thoughts on this?