If your pH is a little high, and you are leery of adding sulfur, you could
mix about 3 inches of peat moss into the top 3 inches of soil. The peat
moss is lower pH, so the pH of the top 6 inches would be in between
what it is overall in the bed and the pH of the peat moss.
Tomato plants have the majority of their feeder roots in the surface soil,
so this would make nutrients that are more available at pH 6.5-7.0 easier
for the plant to take up in that portion of the soil where they take up most
of their nutrition.
(You can see here how tomato plant roots develop:
http://www.soilandhealth.org/01aglib...10137ch26.html
Look particularly at Figure.73. The article also has notes on how disturbed
tap roots, ubiquitous in plants that have been potted up rather than
direct seeded, affects root development in the surface soil.)