...or you could just go with something so overspecced that you can use it as the system grows (which it will!). Trogotronic has their m/15 supply, which has 5 AMPS on each of the 12v rails and 1 amp on the +5, and it's expandable. That might sound extreme, but when you have a P/S like that running at a very low draw, the result is that the P/S puts out less heat...which can affect the overall performance of the build. You also eliminate gradual damage to the P/S's components due to heat, which is a significant synth-killer. And the cherry on the cake is that with the above build, you eliminate all current inrush overloading...which will also pop your P/S if the overage is high enough. No chance of that with the m/15 in that build.
The best solution to power supplies is really simple: get the beefiest one you can! Even if you DON'T use all of the current capacity, there's still some major plusses to having a big honker like the m/15 and other hefty P/Ss out there.