Rwwear is correct. Other than the 'cast' technology and the faceplate design, there was no difference between the fpb 300 and the 300c models. The cx upgrade, however, IS different. I own the upgraded 300cx. Sonically, the Krell cx models are more open sounding and less 'dark' than the earlier fpb's. And, if you want to be 'enticed', then you should definitely buy the 700cx. If you just want great sound, then match the size amp to the size room and speakers you have.