I went from a 2.5bsst2 to a 3B3 and found the change a nice upgrade. Speakers are Mini T. The power increase was welcome as sometimes when I listened at fairly high levels, I could clip the 2.5Bsst2 and that doesn’t happen now. The 3B3 has better separation of instruments in space, is perceptibly quieter, ie, to use the cliched description, the sound comes from an “inky blackness”, and is more relaxed, balanced and neutral. The difference between the 3B3 and 2.5B3 is the power and number of output transistors per channel. Another nice feature of the 3B3 is its shallow depth although it is taller than the 2.5B3. I also pair my 3B3with a tube preamp, a LTA MZ2 and it is a great combination.