I use VTL 450MKII tubed mono blocks. There are a few of us who purchased NOS close-out C2500's lurking about. I would have been happy with the C2300. My understanding is, with the C2500 Mc added a DAC to the package and a few other control features but sound wise the C2500 is pretty much the same as the C2300. So picking the C2500 came down to paying a little more for new and the three year warranty.
Good Luck.
Good Luck.