There's info in other threads about this. For something as powerful as a KitchenAid mixer, make super sure you have a transformer that can handle the wattage. I always recommend the ugly, but powerful, yellow transformers that are used on business sites. We got one for around £70 2 years ago, and it will handle about anything you want.
Now the espresso machine.....as costly as that was, I personally wouldn't risk it on any transformer.
You need to look at the wattage f the most powerful appliance you want to use, and add at least 10% for the initial 'surge'. Then buy the appropriate transformer, remembering that in this case, bigger is better. A good one will be ugly and heavy, but that's the way it goes.
