what is the best power cable for the dCS Puccini

There is no such thing as the best! Performance will vary from system to system. Audition with cable designers that have 30 day money backs until you find a good match. Or, buy well-regarded, popular power cords used and at a good price that you can re-sell if they don't work out, and get back your investment.

I concur with foster_9.
I am using an old foundation research dedicated line conditinoner on mine with good results.
Best wishes

For crystal clear dynamic sound a PC that will enhance digital isolation, power factor and AC power conditioning. Think upper end MIT; at least Magnum AC2. Enjoy;I envy you.