It would surprise me very much if any component is manufactured that is damaged by 240 V. 240V is standard here in the US (along with 120V). My voltages runs as high as 124V/248V and nobody complains of damaged equipment.
Here in the US we used to call outlet power "110 V" and saw some components marked 115V. I think these numbers were conservative, more like a minimum voltage, since many items are more likely to be damaged by undervoltage.
So does your transformer sound good? An oversized transformer can be a good thing to power an amp from. So it may not be a waste of money (as it seem syou suspect).
Jerry