This is what Kitchenaid says about it - also, you will need a transformer, not just an adapter, as the power is different. It does not matter so much for a laptop, for example, but I believe when it comes to something like a mixer, it really can cause problems with the motor power. See more here: www.davidlebovitz.com/2009/06/will-a-kitchenaid-from-america-w/ - read the comments as they explain quite a bit:
Q: Will the US-model KitchenAid mixer work in Europe?
A: Yes, they will work. But we do not recommend it. US units are 110V, Europe runs on 220V. This will slow down the unit causing it to overheat.
Q: Is it possible to use a converter or transformer?
A: That is possible as well, and again, we don?t recommend it.
Q: If I take my mixer out of the country, is the warranty still valid?
A: If you take the unit out of the United States, it does void the warranty.
Q: Are there any other hazards to using a US-model KitchenAid abroad?
A: Hazards include: overheating, possible property damage, and personal injury.
The bottom line is we don?t recommend use of the units outside the US?due to the hazards that could arise.