Bryan certainly makes a good point. Not being familiar with this 300i piece myself I don't know if in fact there are outboard connectors that allow separating the preamp stage from the poweramp section; in fact these connections may not even be available at the rear panel, but only inside. I had previously checked on Krell's website, but I don't see it shown there.
Certainly any stock power cord will allow a component to play music, but not at its' optimum by any means. Just stick with whatever you're comfortable with for the time being; I only mentioned this because if I had kept my 250a & tried to tweak it with better cabling, then I might not have ever sold it. But I didn't believe in any of that "nonsense" either at the time, & probably made a mistake due to my ignorance.