i found that when i had my bass drum flat on the floor my beater actually hit at an angle and wore away really fast until it was just part plastic and part felt hitting the head. but that might have been a problem with the pedal...
also some people might say that if the bass drum is on the floor it might resonate less but i don't think it really matters. now i keep mine between 1-2 inches off just because it keeps the beater hitting the head straight on.
so no i don't think it matters.
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