I have a minimark combo and a 2 x 10 traveler. I also have 2 heads I want to sell in order to buy one great (tube maybe) markbass head. I'm selling my GK 800RB and an Ampeg SVT-200T which I love but is too heavy. I play mostly blues and classic rock and play out occasionally. What should I get used from Markbass in the $550-700 range?