Telling if Bryston pre has upgraded power supply..

Bryston upgraded the power supply on its BP20/BP25 pre-amps a few years back. The following was posted by James Tanner (Bryston VP marketing) on the AudioCircle Bryston owners circle. He is talking about how to recognize by serial number whether a given pre-amp has the upgraded power supply...

"New MPS-1 Power Supply – BP 25 = SN: 251553, BP20 = 221495"
This new power supply is a fanastic upgrade (I had old pre-PS before). It made my system sound so much more alive and open. I hear more detail in my tunes. My BP-25 used to be the weakest link in my system, but not anymore.
How much did the upgrade cost, is you don't mind me asking.
I believe it was $US 300 for the power supply. If you have a very old BP-25 I think you need to upgrade the electronics to use the new PS. I think that costs $US 1000.

In my situation I had purchased my pre-amp new about 4 years ago so I had the latest electronics on the pre-amp. The only thing lacking on mine, from todays latest and greatest model, was the new power supply. You can email Bryston and ask them if you pre-amp has the latest electronics.