The tubes shouldn't be a problem, but excessive moisture can wreck a lot of other things. Thorman's suggestion is sound. This may seem counter intuitive, but an air conditioner works great for keeping the moisture levels down. The heat goes outside instead of indoors as with a dehumidifier
tubes and moisture
I run almost all tube based gear. I live in a very moist,damp basement apartment on coastal northern California. I already use a dehumidifier every other day and cover my gear with towels after every listening session overnight and during the day while at work. Is this enough protection and what is the worst scenario here in terms of gear damage?