I was cool with setting liquids on my amp over 30 years ago, when I had $100 wrapped up in a second hand amp and didn't know any better. I don't have top of the line gear now but I'm not willing to risk ruining it. The drink might not get spilled, but cold drinks sweat and the condensation...so on and so forth. The risk of frying your amp might be minimal, but it is still there and easily preventable.
