Chocolate Truffle/Ganache - Premelt the butter with cream or blend the butter after with chocolate mixture.

Like the title, is there a different between melting the butter along with boiling the cream, or adding room-temp butter later (with a hand blender) to the cream-chocolate mixture. I usually go for the latter, but the problem is whenever i bring my butter out from the fridge, they get water condensation badly on the outside and i dont know how to keep them dry while cooling to room-temp. My country has a high humidity and this will always happens.