Most equipment meant for 100 Volt operation can probably operate on 110-120 Volt systems without problems. You should check with the manufacturer for specific equipment. I would hestitate to operate a power amplifier on lower or higher Voltage than spec'd since this will affect power output and distortion components. Using a power "converter" on anything other than items such as source components is not a great idea since most converters cannot supply sufficient current for anything larger than a CD player. In the long run when you find a high current converter it will probably be cheaper to buy a new amplifier. If you are shopping online and trying to save a few bucks, remember you have no warranty when the unit leaves its original local destination.

I lived in Europe for a few years and powered my US-purchased system through a step-down transformer. The amp was an Adcom GFA-555. Sounded just fine thank you. I seriously doubt you'll have any difficulties powering your Leben amp with a 2000 watt transformer. The warranty may disallow this practice though.

If you ask the store where you'll buy the Leben amp to sell you the one with a 120v power supply, they will be more than happy to do so.

Consult the manufacturer for any problems that might arise from the use of a converter. The 2k watt unit should provide sufficient amperage. Consider the disadvantage of no warranty service. A recent column in Stereophile discussed the cost vs. gain of such a purchase. Possibly somone can give a link to that article.