+1.
Any knowledgeable luthier will tell you this.
Although, IME, basses sound better a bit on the dry side. Think about it. The wetter the wood, the harder it is for the vibrations to move through it. The drier it is, well.......
I live in a pretty dry area and my basses always sound best here.
As Flanning says, consistency is the ticket...dry or humid.
Radical changes in humidity can blow a bass apart. That's why you have be careful with Damp-It's and humidifiers.
Stick your bass in a room with a humidifier for a few day and take it out for an outside concert in 90 degree dry heat and watch the result.
the dry side is the dangereous side... (ok, i'm a newbie, but still... sounds rather logical to me...)