At present I use a Sumiko Blackbird MC cartridge which is paired with a MM Phono Stage (ProJect Tube Box S). I am considering replacing it with a Bryston Phono Stage. My choices are the onboard stage with my 135sst2 integrated amp or the newer separate PS-3 Power Supply and BP2 preamp. If I purchase the BP2 as an MM only at this point, can it be upgraded at a later date if I should ever change to a cartridge requiring a MC preamp? Would there be a noticeable difference in sound quality between the onboard or separate preamp considering they are the same component other than the separate power supply?