Hi Kingpin,
If your cartridge has a 3.6mV output, and your phonostage offers a gain of 100, then the output voltage of your phonostage will be 360mV (0.36V).
The input sensitivity of the Sig 30.2 integrated is approx. 0.5Vrms, so while this will work, you'll probably find that you need to really turn up the volume when you want to play it loud, and you still won't be able to reach the full 30Wrms output of the Sig 30.2 (but depending on how loud you play and the sensitivity of your speakers, you might not need to). For example, if you have high-efficiency speakers and you don't play it very loud, it probably will work out fine!
Hopefully you can get a return-policy on the phonostage to make sure it works out for you...
Hope this helps,
Vinnie