As for the above post: Most companies should provide a RFI filter at the incoming connecting cable side or in the cable itself. Secondly as far as cost is concerned, I think isolating all the nasties that can come from pwr supplies should give piece of mind when it comes to your gear and the money invested. Just my opinion.
Seperate Power Supply and Preamps
Several of the top end tube preamps like Hovland, Joule Electra, Herron, and Lamm have no seperate power supply. Others like First Sound Presence, Atma-sphere, Cary, have seperated out the power supplys with some of their models. What are the advantages of this sonically or is this just a physical limitation problem with the manufacturer?