I have a P300 and a P600 and I have two dedicated lines from the fuse box terminated to a Mirainco IEC pluged directly into them. You would not believe the results in eliminating one power cord (even the best one) and a connection.
I used a Electraglide Fatboy 2000 Silver.....that beat out my SR Designer's Reference Squared PC. But the best upgrade, if you can swing it financially, is to go to the P1000. I did just that and cannot believe the difference! It really is a BIG upgrade sonically IMO.