I never thought about it but I can imagine that power and cables would probably have a much greater impact on digital rather than on analog gear.
Clean power does seem to affect digital - well it has in my experience. I suspect switched mode power supplies can be a problem. However, before spending $3000, I'd suggest you experiment with say $100 monster power bar filter first and see if it makes an audible difference. FWIW the power supply in the DAC1 is linear (not switched mode like a DVD player) and it runs quite hot - like a hot mug of coffee to the touch. That and the signficant weight of the little box suggests that it probably has a decent power supply to begin with.
Another avenue to check is to ask a question on Head-Fi org to Elias Gwinn (Benchmark engineer). I expect he will tell you that the DAC1 is designed to work in studios with dirty power and should not need conditioning in all but very extreme cases.
Good Luck!