I have the B&K 307, as well as the B&K 220M monoblock: I don't think you'll hear the difference between the 307 and the 7250.
Also, the normal rap on B&K amps is that they're not as strong as an equivalent Krell or Bryston (both of which have very conservative ratings; the normal line is the B&K amps are more tube-like than the higher-end solid states.
My recommendation for an upgrade, if you need it, is the Powerpac 250 Brystons: you can position these behind the speakers, minimizing the amplified signal (lower cost, better sound).
Also, the normal rap on B&K amps is that they're not as strong as an equivalent Krell or Bryston (both of which have very conservative ratings; the normal line is the B&K amps are more tube-like than the higher-end solid states.
My recommendation for an upgrade, if you need it, is the Powerpac 250 Brystons: you can position these behind the speakers, minimizing the amplified signal (lower cost, better sound).