bryston bp5 vs bp25?

Does anyone know the difference in sound quality?
I still own a BP5 and BP20 - both are good preamps at their price point - a true window to your source. The BP20 (same as the BP25)is a lot smoother as a result of the different circuitry and separate power supply. Soundstage is also wider and deeper - excellent synergy with Bryston power amps.
I've owned the Bryston 0.5B as well as the BP20. Purchasing a BP20 or BP25 used is one of the great values in audio. The BP20 is a very significant improvement in black background and smooth, refined sound. The 0.5B was harsh and forward in comparison. This is primarily attributed to the separate power supply IMO.