I just finished putting in a dedicated line for my system (had started a few weeks back). Quite simple really to do, didn't take long at all (quite unlike these CDpro kits).

Anyway, I knew that my system could be improved with this, because the circuit it was on fed nearly my whole house (all in series!). The outlets were not grounded before, they used really old cotton wrapped BX with aluminum housing. I ran some 10awg romex w/ground and wired in some Hubbel cryo'd outlets.
My fears were that I was going to give a more immediate path for the grid noise to my system. I knew there were some gains to be had even so but I didn't think they were going to be very large. I am surprised by how much it did improve details. Less noise for sure, it is one of those things you don't know until it is gone. Unfortunately it didn't do anything for my acoustics.
