So i've been borrowing my friend's GK backline 600 and running it through an Ampeg svt410he. It's always been plenty loud but doesn't give off much vibe and could sound a little better. I'm looking to get something with at least a tube pre in the 300-600 dollar range. I've looked at the bugera BVT and the lower end ampeg svts, hartke's, ashdowns, as well as old fender bassman heads and old ampeg V4bs etc...does anyone have opinions as to what would be the best? I know bugera is releasing an all tube SVT copy in the 6-700 dollar range, but i'm not sure if i should go with one of the lower end rackmountable tube pre heads or just sack up and save for something all tube. I play in a folk rock band but we just added another guitar player and have been playing bigger shows so i need a good amount of power. I really like the james jamerson sound (but my b100r isn't loud enough for most gigs) and i also like the paul mccartney and kings of leon bass tones....any ideas on something vintage thats cheap and tube? or does anyone know about the all tube Bugera head?