Dude, there is a big difference in quality, my best friend has the 540 and you say it sounds better?? No way. The 630 sold new for $1000.00, and there are many places on the net still selling them for $879.95 without the footpedal and power supply. Check out the link I left for the options it has or ask yamaha and they will tell you the definate advantages of the 630.