Which is the best 220v to 110v transformer for a guitar amp?

I bought a guitar amp Line 6 Spider III 30W in the US last week. I live in Asia where the power supply is 220v 53Hz. I was wondering which is the best 220v to 110v transformer I can use to use this gear here in Asia? I am afraid to lose my 199 USD investment due to a electrical problem.
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