Ken uses a SUT that doesn't really have a lot of boost because I think he believes that as the step up increases, the loss is SQ is too great.That's been our experience too. The more stepup you use the less bandwidth you get.
We regularly run cartridges that are 0.2mV. If you have an SUT you should be able to get in that same range quite easily. The only thing you would have to work on is the loading of the SUT, with which Ken might be able to help you. We use Jensen Transformers when we use an SUT; they have published a pdf file of all the loading values for a great deal of different cartridges including Lyras.
Keep in mind that 0.25mV is 6dB less than 0.5mV; that means you'll have to run the volume control up a few notches to get the same sound pressure. I don't think you'll have any problems doing that :)