Yes you have to drop the voltage, 80V is a max for the Geckos, going over that will risk blowing the drives. There may be other tappings on your transformer so that you can select lower output voltages or there may even be tappings on the Input side for higher voltages than you are using, either may drop the output. If your transformer cant be tapped for lower output then you would need to get another transformer to drop its output down to a voltage you required, this however would be a waste of time as you would now have two transformers to do one transformers job, so you would be as well taking out the original one and replacing it with a new one. You have to remember also that the AC voltage output of the transformer will have to be a lot lower than the voltage you require, once rectified and smoothed the DC voltage will be 1.4 times (approx) greater than the AC transformer output.
Hood