A totally free improvement would be moving those vandies away from the back wall (like a couple of feet away). And if I remember correctly, vandies aren't shielded, so you're probably going to get some blotches on your tv screen.
Have you considered a tubed pre in your quest to get to that warmer, rounder sound (that's the tubed pre's strong point). Lot's of used, high quality options at a variety of price points.
Good luck and have fun.
