Am I going to need a step up transformer?

You should be fine. From the KAB gain calculator web page:
Chart of Typical Gain Values (relative to 5cm/sec):
Output Gain
3 - 6 mV 36dB
1 - 3 mV 43dB
0.3 - 1.0 mV 53dB
0.15 - 0.3 mV 60DB

Of course, YMMV. For more details, click here.

Although there is no standard method for measuring output, so the two numbers may not be an "apples to apples" comparison, the difference appears to be quite small. Also, 70 db is quite a lot of gain for a phonostage. You should have plenty of gain for that cartridge. A friend uses it and really likes the Dynavector.