I have been using a T2 power cord on my Pass Labs XP10 Preamp for quite some time now. This power cord has been recommended by SR and by most of the posters on this thread.
But, sprinkled throughout this thread there are some who are using the Precision Ref Power cord on thier Preamp.
Well, I tried one on mine and I have got to tell you there was a pretty big improvement. Improvement in areas of better soundstage, clearer highs and better definition all around.
I have also tried the Hologram A on the preamp and found the upper bass to be too boomy.
So, it is amazing how there is so many "right" cables for different equipment.