Pass Labs vs Bryston BP25

Anyone care to explain the difference's between these two preamps and what one could expect to hear when compared to each other.
With regard to the above thread it should read
Pass Labs X1 vs Bryston BP25
Have not heard the Pass Labs XI but I have heard the BP25 with the old power supply and now with the new power supply (MPS-1 I think). The new power supply has made significant improvements in the BP25. I can hear more detail in my music. The preamp sounds fantastic to me now. I am no longer considering changing preamps. Very happy camper with BP25/7B-SST combo.