I am a big believer in dedicated lines! ... The more the better, but the biggest difference will be with the 1st. I have three: one for the front end and one for EACH of my large Krell amps. (one 20 amp and two 30 amp lines)
As far as your question about one for digital and one for the preamp: I am sure that it wouldn't be a bad idea, but I found that the inexpensive PAC Idos, which separates the digital grunge from the analog equipment, really works.
As far as your question about one for digital and one for the preamp: I am sure that it wouldn't be a bad idea, but I found that the inexpensive PAC Idos, which separates the digital grunge from the analog equipment, really works.