You won't need a transformer. Not if you're talking about line voltage. Line voltage is nominal, as in uncalibrated, as in it varies. What is called 110 here in the US can turn out to measure lower. (Occasionally even quite a bit lower, in what is called a brown-out.) Which, strangely enough, voltage running a little low like that turns out to be a much bigger problem than voltage that runs high.
This is because, first thing your amp does is run the incoming AC through its power supply. The power supply converts the AC to DC. Everything actually runs on this DC power supply. CD player, turntable, DAC, your laptop for that matter. It all runs on DC. As such it is all pretty darn near immune to AC voltage- unless said voltage drops too low. Damage from high voltage however only happens when voltage spikes crazy high. Think lightning. Some tens of volts though is nothing. I travel, and have plugged in many times to 200-220v, none of my 110v gear was ever harmed in the least.
