Martin, my pre is digital (part of the dac), however normal analogue pre-amps have sensitive curcity inside as well, they also don't take a lot of power and are more sensitive to mains bourne noise in my reckoning, a 500va would cover nearly all digital/pre requirements no probs, else just stick one on the power amp/int, you need to experiment to see how it works best for you.

Digital curcitry responds the best in a pound for pound way I feel. WM