While the A3-250 will be a nice jump over the sub 10, I don't think it will be a spectacular leap. If money is tight, it might be worth it, but if you can make the stretch to a A3-300, or a Outlaw Audio LFM-1 Plus, or Hsu Research VTF2 mk3, try to do that. But the A3-250 should definitely have a edge over the sub 10, and if that is what you are mostly after, no reason to spend a lot more money.